Flynn, Ethan and Jeremy have some marbles. The ratios of their marbles are as follows:

Flynn : (Flynn + Ethan + Jeremy) = 3 : 7
Ethan : (Flynn + Jeremy) = 1 : 5

Jeremy has 90 marbles more than Ethan. In the end, Jeremy gives away all he has to Ethan and Flynn so that both Ethan and Flynn end up with the same number of marbles, how many marbles has Ethan received from Jeremy?

Ethan	Jeremy	Flynn	Total
4x6		3x6	7x6
1x7	5x7		6x7
7 u	17 u	18 u	42 u

The total number of marbles is repeated.  Make the total number of marbles the same.  LCM of 7 and 6 is 42.

Number of marbles that Jeremy has more than Ethan
= 17 u - 7 u
= 10 u

10 u = 90

1 u = 90 ÷ 10 = 9

	Ethan	Jeremy	Flynn
Before	7 u	17 u	18 u
Change	+ 14 u	- 17 u	+ 3 u
After	21 u	0 u	21 u

Number of marbles that Ethan has received from Jeremy
= 21 u - 7 u 
= 14 u
= 14 x 9
= 126

Answer(s): 126