Posted by Erica on .
Math 221  Ms. Sue, Sunday, July 13, 2014 at 2:24pm
I've done several problems for you. Now it's your turn.
How do you think this problem should be solved?
Answer this Question I was thinking that I should multiply the numerators and denominators

Math 221 
Steve,
as with most problems involving fractions, work first with the denominators. They cannot be added or subtracted unless they all have the same denominator.
5/12 + 7/9
The GCD(12,9) = 36. So, what you have is
15/36 + 28/36
Now all the "units" are the same. Just as you cannot add apples and oranges, you cannot add twelfths and ninths. But you can add a bunch of 36ths. Since 15+28=43, the final answer is just 43/36.
Or, if you must, 1 7/36