Box F contains 4 gold balls and 3 pink balls. Box G contains 31 gold balls and 14 pink balls. How many pink balls and gold balls must be removed from Box G to put into Box F so that 50% of the balls in Box A are gold and 80% of the balls in Box G are gold?

	Box F		Box G
	Gold balls	Pink balls	Gold balls	Pink balls
Before	4	3	31	14
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	4 p	1 p

50% = ⁵⁰₁₀₀ = 12

80% = ⁸⁰₁₀₀ = 45

Number of gold balls = 4 + 31 = 35 

Number of pink balls = 3 + 14 = 17 

1 u + 4 p = 35 --- (1)

1 u + 1 p = 17 ---(2)

(1) - (2)
(1 u + 4 p) - (1 u + 1 p) = 35 - 17
4 p - 1 p = 18
3 p = 18

1 p = 18 ÷ 3 = 6

From (2):
1 u + 1 p = 17
1 u + 1 x 6 = 17
1 u + 6 = 17

1 u = 17 - 6 = 11

Number of pink balls to be removed from Box G to Box F
= 14 - 1 p
= 14 - 1 x 6
= 14 - 6
= 8

Number of gold balls to be removed from Box G to Box F
= 1 u - 4
= 11 - 4
= 7

Total number of pink and gold balls to be removed from Box G to Box F
= 8 + 7
= 15

Answer(s): 15