Container F contains 7 pink balls and 15 black balls. Container G contains 97 pink balls and 41 black balls. How many black balls and pink balls must be moved from Container G to put into Container F so that 50% of the balls in Container A are pink and 70% of the balls in Container G are pink?

	Container F		Container G
	Pink balls	Black balls	Pink balls	Black balls
Before	7	15	97	41
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	7 p	3 p

50% = ⁵⁰₁₀₀ = 12

70% = ⁷⁰₁₀₀ = 710

Number of pink balls = 7 + 97 = 104 

Number of black balls = 15 + 41 = 56 

1 u + 7 p = 104 --- (1)

1 u + 3 p = 56 ---(2)

(1) - (2)
(1 u + 7 p) - (1 u + 3 p) = 104 - 56
7 p - 3 p = 48
4 p = 48

1 p = 48 ÷ 4 = 12

From (2):
1 u + 3 p = 56
1 u + 3 x 12 = 56
1 u + 36 = 56

1 u = 56 - 36 = 20

Number of black balls to be moved from Container G to Container F
= 41 - 3 p
= 41 - 3 x 12
= 41 - 36
= 5

Number of pink balls to be moved from Container G to Container F
= 1 u - 7
= 20 - 7
= 13

Total number of black and pink balls to be moved from Container G to Container F
= 5 + 13
= 18

Answer(s): 18