Glen and Michael shared some marbles in the ratio of 3 : 8. After both each gave away 36 marbles to their brother, the ratio of the number of marbles Glen had to the total number of marbles left was 1 : 5. How many marbles did the two boys have at first?

	Glen	Michael	Difference
Before	3x3 = 9 u	8x3 = 24 u	5x3 = 15 u
Change	- 36	- 36
After	1x5 = 5 u	4x5 = 20 u	3x5 = 15 u

Number of marbles that Glen and Michael each gave to their brother is the same.

The difference in the number of marbles at first and in the end between Glen and Michael remains unchanged.  Make the difference in the number of marbles the same.  LCM of 5 and 3 is 15.

Number of marbles that Glen gave to their brother
= 9 u - 5 u
= 4 u

4 u = 36

1 u = 36 ÷ 4 = 9

Number of marbles that the two boys had at first
= 9 u + 24 u
= 33 u
= 33 x 9
= 297

Answer(s): 297