Rename 3/4 and 2/5 using 20 as the common denominator

Let’s use 2 methods to do this:

First, let’s try cross multiplying:

3/4=x/20

2/5=x/20

20 times 3 = 60

60 divided by 4 is 15, so 3/4 = 15/20

20 times 2 = 40

40 divided by 5 is 8, so 2/5 = 8/20

The next method:

What time 4 equals to 20? What times 5 equals to 20?

4 times FIVE equals to 20

For the fraction of 3/4, multiply the numerator and the denominator by five to get your answer of 15/20.

5 times FOUR equals to 20

For the fraction of 2/5, multiply the numerator and the denominator by four to get your answer of 8/20.

Hope I helped!

the answer is 62