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Question 200061: add and subtract the following fractions.
2/3+5/7
3/4+7/12
4/9-1/8
Answer by jerrybassmasta(14)   (Show Source):
You can put this solution on YOUR website! Adding and subtracting fractions are very simple, that is if yo know only one rule.
The rule is to have common denominators.
2/3+5/7
The common denominator for 3 and 7 will be 21. The easiest way is to just multiply them together.
So you have 21, then you ask yourself. How many times did 3 go into 21. (7 times) So you multiply 2 by 7 as well. Same for the other side. How many times does, 7 go into 21. (3 times) So you multiply 5 by 3.
Now you have.
14/21+15/21 Now you can add them as normal numbers. (Remember you don't add the denominators)
29/21
Reducing them are quite simple as well, all you do as subtract the top number from the bottom number.
1 and 8/21
3/4+7/12
Using the same steps you should start off with.
9/12+7/12
16/12
1 and 4/12 You can also simply simplify it to.....
1 and 1/3
4/9-1/8
32/72-9/72
21/72
7/24
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