There were green, yellow and brown marbles in a box. Sean put another 7 green marbles and 11 brown marbles in the box, then the ratio of the number of yellow marbles to the number of brown marbles became 4 : 3. Then, he doubled the number of green marbles and removed 27 brown marbles. The ratio of the number of green marbles to yellow marbles became 2 : 1. He counted and found that there were a total of 48 marbles left in the box. Find the number of green marbles that he had in the end.

	Green marbles	Yellow marbles	Brown marbles	Total
Before	4 u - 7	4 u	3 u - 11
Change 1	+ 7		+ 11
After 1	1x4 = 4 u	4 u	3 u
Change 2	+ 1x4 = 4 u		- 27
After 2	2x4 = 8 u	1x4 = 4 u	3 u - 27	48

The number of yellow marbles remains unchanged. Make the number of yellow marbles the same. LCM of 1 and 4 is 4.

Total number of marbles in the end
= 8 u + 4 u + 3 u - 27
= 15 u - 27

15 u - 27 = 48
15 u = 48 + 27
15 u = 75

1 u = 75 ÷ 15 = 5

Number of green marbles in the end
= 8 u 
= 8 x 5
= 40

Answer(s): 40