Box R contains 14 pink balls and 10 grey balls. Box S contains 28 pink balls and 16 grey balls. How many grey balls and pink balls must be transferred from Box S to put into Box R so that 50% of the balls in Box A are pink and 75% of the balls in Box S are pink?

	Box R		Box S
	Pink balls	Grey balls	Pink balls	Grey balls
Before	14	10	28	16
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	3 p	1 p

50% = ⁵⁰₁₀₀ = 12

75% = ⁷⁵₁₀₀ = 34

Number of pink balls = 14 + 28 = 42 

Number of grey balls = 10 + 16 = 26 

1 u + 3 p = 42 --- (1)

1 u + 1 p = 26 ---(2)

(1) - (2)
(1 u + 3 p) - (1 u + 1 p) = 42 - 26
3 p - 1 p = 16
2 p = 16

1 p = 16 ÷ 2 = 8

From (2):
1 u + 1 p = 26
1 u + 1 x 8 = 26
1 u + 8 = 26

1 u = 26 - 8 = 18

Number of grey balls to be transferred from Box S to Box R
= 16 - 1 p
= 16 - 1 x 8
= 16 - 8
= 8

Number of pink balls to be transferred from Box S to Box R
= 1 u - 14
= 18 - 14
= 4

Total number of grey and pink balls to be transferred from Box S to Box R
= 8 + 4
= 12

Answer(s): 12