What is the sum of 3/5 and 7/8?

First of all we need to find a common denominator. This is the smallest number that can be divided by both 5 and 8, which is 40.

24/40 + 35/40

Method: 5 goes into forty 8 times and so we must multiply the 3 by 8 as well. 8 goes into forty 5 times and so we must multiply the 7 by 5 as well.

As we have a common denominator we can now add the numerators.

24/40 + 35/40 = 59/40