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#### Maaso

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I failed Math every year in school, so I don't know what any of this means. I'm reading the explanations here in my math book, and I still don't understand. And I don't have these buttons on my calculator so I'm lost.

Here is an example...

Simplify complex fractions
7/12 + 5/16 = 43/48 Those are fractions, not division. The examples in the book are nothing like the problems I have to do. Another one is -5/9 - 14/15 = -67/45, I don't understand any of this. I know it has something to do with cross multiplying...I don't know what any of that is either.

If somebody could help me understand this, I would be forever indebted to you.

#### Rhodes

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It is not algebra its just operations on fractions, got a video link for you that may help.

http://video.google.com/videosearch?q=How+to+add+and+subtract+fractions&oe=utf-8&rls=org.mozilla:en-US fficial&client=firefox-a&um=1&ie=UTF-8&ei=WliTSoLJPMOHtgfwhPVL&sa=X&oi=video_result_group&ct=title&resnum=4&ved=0CBsQqwQwAw#

The second problem is best looked at like this;
(-5/9) - (+14/15) = (-67/45) 67 is a prime number and cannot be reduced. To get here;
[(-5/9)x(5/5)] - [(+14/15)x(3/3)] Reach a common denominator of x/45 .... 5/5=3/3=1 so not changing anything
(-25/45) - (+42/45)
[(-25) - (+ 42)]/45 Since you are subtracting a positive number from a negative number it translates into (-1)x(25+42)=(-1)x(67)= -67
-67/45
Best i can do for ya man, vidoes look good.

#### NDS

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I failed Math every year in school, so I don't know what any of this means. I'm reading the explanations here in my math book, and I still don't understand. And I don't have these buttons on my calculator so I'm lost.

Here is an example...

Simplify complex fractions
7/12 + 5/16 = 43/48 Those are fractions, not division. The examples in the book are nothing like the problems I have to do. Another one is -5/9 - 14/15 = -67/45, I don't understand any of this. I know it has something to do with cross multiplying...I don't know what any of that is either.

If somebody could help me understand this, I would be forever indebted to you.
You have to find a common denominator for the fractions in order to add them.
First look for common a multiple ot 12 and 16 that is also a multiple of 48. In this case it's easy because 12x4 and 16x3 are both equal to 48x1, they are all 48. When you multiply the denominator you multiply the numberator by the same value, so
7/12 becomes 7x4/12x4 + 5x3/16x3 after you multiply this becomes 28/48+ 15/48 add the numerators and keep the denominators (do not add the 48s) you get 28+15/48 which simplifies to 43/48

The subtraction is the same. The common denominator is 45 (9x5 and 15x3) -5x5/9x5 - 14x3/15x3 becomes -25/45 - 42/45 . Next, combine the numerators keeping the denominators -25 - 42 /45 = -67/45

Teaching math over the internet isn't easy; it's too bad we can't have just a few minutes with some scratch paper. Check and see if your local community college offers math tutors, they are often free if you go to the school.

Good luck with math, if you have any more questions feel free to PM.

#### Loopster

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I failed Math every year in school, so I don't know what any of this means. I'm reading the explanations here in my math book, and I still don't understand. And I don't have these buttons on my calculator so I'm lost.

Here is an example...

Simplify complex fractions
7/12 + 5/16 = 43/48 Those are fractions, not division. The examples in the book are nothing like the problems I have to do. Another one is -5/9 - 14/15 = -67/45, I don't understand any of this. I know it has something to do with cross multiplying...I don't know what any of that is either.

If somebody could help me understand this, I would be forever indebted to you.
To add/subtract fractions, you have to make the bottom numbers match (the demominators). In this instance both 12 and 16 will go into 48. 12x4=48 and 16x3=48. You have have to multiply the top number by the same as you do the bottom number, so 7x4=28. The first fraction is 28/48. The second fraction would be 5x3=15 or 15/48. Now that both fractions are over a common demominator, you can add the top numbers (the numerators). 28+15=43, so the sum would be 43/48.

The second problem is worked in the same way. 9 and 15 (the demominators) will both go into 45. 9x5=45 and 15x3-45. Since you have to multiply the numerators by the same thing you multiply the denominators by, 5x5=25 and 14x3=42, and 42+25=67, so the sum would be 67/45.

Dont let the minus throw you. -x-y is the same as saying -(x+y).

Hope this helps.

#### Maaso

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Thanks Roades, I think I understand a little more now. I'm still very slow.

Let's go back to that first problem I had....

7/12 + 5/16 = 43/48

The lowest common denominator...it's just the lowest number that both of those will multiply to? Which in the case would be 48? 4 x 12 = 48 and 3 x 16 = 48. Then you just multiply the top numbers by the same number? 7 x 4 = 28 and 5 x 3 = 15? Then just add them all together?

28/48 + 15/48 = 43/48

That makes more sense to me than the stuff in the book.

#### Loopster

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Oh, NDS beat me to the punch.

#### Maaso

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Lol, you guys were all writing replies while I was figuring this out.

-x-y is the same as saying -(x+y).
That actually confused me more...

I'm not sure if they offer tutors or not NDS, I'm sure they do. But this is only the second Math class so far, not sure who, or where to ask for it.

#### Loopster

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Lol, you guys were all writing replies while I was figuring this out.

-x-y is the same as saying -(x+y).
That actually confused me more...

I'm not sure if they offer tutors or not NDS, I'm sure they do. But this is only the second Math class so far, not sure who, or where to ask for it.
Sorry 'bout that.

#### Rhodes

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Thanks Roades, I think I understand a little more now. I'm still very slow.

Let's go back to that first problem I had....

7/12 + 5/16 = 43/48

The lowest common denominator...it's just the lowest number that both of those will multiply to? Which in the case would be 48? 4 x 12 = 48 and 3 x 16 = 48. Then you just multiply the top numbers by the same number? 7 x 4 = 28 and 5 x 3 = 15? Then just add them all together?

28/48 + 15/48 = 43/48

That makes more sense to me than the stuff in the book.
You got it nailed.

#### Maaso

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Sorry 'bout that.
-(x+y).

Actually, I think I understand it just by looking at it. Since a negative minus a negative = a positive. You basically rewrote it so you just add the two, then put a negative beside them. I'm probably not explaining it that well, but I understand.

Thank you all for the replies, I have to do 125 of these problems, then I get to dive into Exponential expressions....

#### Loopster

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125 huh? Looks like you'll be up a while. If you need any more help just holler.

#### NDS

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Sorry 'bout that.
-(x+y).

Actually, I think I understand it just by looking at it. Since a negative minus a negative = a positive. You basically rewrote it so you just add the two, then put a negative beside them. I'm probably not explaining it that well, but I understand.

Thank you all for the replies, I have to do 125 of these problems, then I get to dive into Exponential expressions....
No, be careful with signed numbers (+ or - ) A negative minus a negative will be negative. I think you're confusing the rules for addition and subtraction with the rules for multiplication and division.

#### Mike_AZ

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Actually, I think I understand it just by looking at it. Since a negative minus a negative = a positive. You basically rewrote it so you just add the two, then put a negative beside them. I'm probably not explaining it that well, but I understand.
A negative minus minus a negative does not equal a positive. It equals a a "bigger" negative. For example -20-30 =-50. What loopster was pointing out is that it can also be expressed as -(20+30) =-50. In other words when you subtract a number from another negative number it is the same as adding the two numbers and then putting a negative symbol in front of it. I hope that made sense as I have had more than a few drinks tonight.

#### Loopster

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I'm sorry again. I should've just left off the parentheses thing. Don't get hung up on that.

-5-4=-9
-5+4=-1
-4-5=-9
-4+5=1

Its just plain old adding and subtracting.

#### Maaso

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Thanks for all the help guys, I only missed 4 out of all 125. The next chapter looks even tougher though....

#### Mstr33t

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I can't do algebra to save my life, it's the main reason I haven't done anything college related...

#### Maaso

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One more bitch....

Why did they change the signs for multiplying every year?

When I was doing Math years ago, the sign for it was "x" now they use a dot, and a star looking sign. And don't even use a sign sometimes, like... AB + CD is A x B + C x D

#### Mstr33t

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Math teachers are gay, that's why. What? I've had nothing but bad experiences trying to learn math...

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