There were pink, red and brown balls in a container. Sean put another 5 pink balls and 7 brown balls in the container, then the ratio of the number of red balls to the number of brown balls became 5 : 3. Then, he doubled the number of pink balls and removed 24 brown balls. The ratio of the number of pink balls to red balls became 2 : 1. He counted and found that there were a total of 84 balls left in the container. Find the number of pink balls that he had in the end.

	Pink balls	Red balls	Brown balls	Total
Before	5 u - 5	5 u	3 u - 7
Change 1	+ 5		+ 7
After 1	1x5 = 5 u	5 u	3 u
Change 2	+ 1x5 = 5 u		- 24
After 2	2x5 = 10 u	1x5 = 5 u	3 u - 24	84

The number of red balls remains unchanged. Make the number of red balls the same. LCM of 1 and 5 is 5.

Total number of balls in the end
= 10 u + 5 u + 3 u - 24
= 18 u - 24

18 u - 24 = 84
18 u = 84 + 24
18 u = 108

1 u = 108 ÷ 18 = 6

Number of pink balls in the end
= 10 u 
= 10 x 6
= 60

Answer(s): 60