Brandon, Valen and Rael have some marbles. The ratios of their marbles are as follows:

Brandon : (Brandon + Valen + Rael) = 1 : 4
Valen : (Brandon + Rael) = 1 : 5

Rael has 30 marbles more than Valen. In the end, Rael gives away all he has to Valen and Brandon so that both Valen and Brandon end up with the same number of marbles, how many marbles has Brandon received from Rael?

Valen	Rael	Brandon	Total
3x3		1x3	4x3
1x2	5x2		6x2
2 u	7 u	3 u	12 u

The total number of marbles is repeated.  Make the total number of marbles the same.  LCM of 4 and 6 is 12.

Number of marbles that Rael has more than Valen
= 7 u - 2 u
= 5 u

5 u = 30

1 u = 30 ÷ 5 = 6

	Valen	Rael	Brandon
Before	2 u	7 u	3 u
Change	+ 4 u	- 7 u	+ 3 u
After	6 u	0 u	6 u

Number of marbles that Brandon has received from Rael
= 6 u - 3 u 
= 3 u
= 3 x 6
= 18

Answer(s): 18