Amanda and Joe have some books in the ratio 3:7. Amanda has 72 less books than Joe. How many books must Joe give to Amanda so that they will have the same number of books?

Answer 1

A/J= 3/7
A + 72 = J
so
A / (A+72) = 3/7
7 A = 3 A + 3*72
4 A = 3* 6*12
A = 3*6*3 = 54
J = 54+72 = 126
sum = 180
so each has 90
126 = 90 = 36

Answer 2

Amanda's books --- 3x
Joe's books ---- 7x

7x - 3x = 72
4x = 72

take it from here

Answer 3

I mean 126 - 90 = 36