Wesley and Ben shared some stamps in the ratio of 3 : 8. After both each gave away 21 stamps to their sister, the ratio of the number of stamps Wesley had to the total number of stamps left was 1 : 6. How many stamps did the two boys have in the end?

	Wesley	Ben	Difference
Before	3x4 = 12 u	8x4 = 32 u	5x4 = 20 u
Change	- 21	- 21
After	1x5 = 5 u	5x5 = 25 u	4x5 = 20 u

Number of stamps that Wesley and Ben each gave to their sister is the same.

The difference in the number of stamps at first and in the end between Wesley and Ben remains unchanged.  Make the difference in the number of stamps the same.  LCM of 5 and 4 is 20.

Number of stamps that Wesley gave to their sister
= 12 u - 5 u
= 7 u

7 u = 21

1 u = 21 ÷ 7 = 3

Number of stamps that the two boys had in the end
= 5 u + 25 u
= 30 u
= 30 x 3
= 90

Answer(s): 90