5th grade
posted by brianna on .
can you explain to me how to add and subtract fractions like 2/5 + 5/12 or 7/12  8/9? i'm having trouble on this and i'm always forgetting how to do it.

You need to find the common denominator.
2/5 + 1/12
What is the smallest number that can be divided by both 5 and 12? It helps to look at the multiples of the larger number. Then find which of those number is divisible by 5.
12, 24, 36, 48, 60, 72??
Did you get 60? Good, because 60 is the common denominator.
2/5 = ?/60
Now, to find the numerator. Divide 60 by 5. That's 12, right? Next multiply 12 * 2
2/5 = 24/60
5/12 = 25/60
24/60 + 25/60 = 49/60
Please read the above carefully and then try to solve the second probem.
7/12  8/9