Box G contains 11 black marbles and 7 pink marbles. Box H contains 38 black marbles and 20 pink marbles. How many pink marbles and black marbles must be transferred from Box H to put into Box G so that 50% of the marbles in Box A are black and 75% of the marbles in Box H are black?

	Box G		Box H
	Black marbles	Pink marbles	Black marbles	Pink marbles
Before	11	7	38	20
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	3 p	1 p

50% = ⁵⁰₁₀₀ = 12

75% = ⁷⁵₁₀₀ = 34

Number of black marbles = 11 + 38 = 49 

Number of pink marbles = 7 + 20 = 27 

1 u + 3 p = 49 --- (1)

1 u + 1 p = 27 ---(2)

(1) - (2)
(1 u + 3 p) - (1 u + 1 p) = 49 - 27
3 p - 1 p = 22
2 p = 22

1 p = 22 ÷ 2 = 11

From (2):
1 u + 1 p = 27
1 u + 1 x 11 = 27
1 u + 11 = 27

1 u = 27 - 11 = 16

Number of pink marbles to be transferred from Box H to Box G
= 20 - 1 p
= 20 - 1 x 11
= 20 - 11
= 9

Number of black marbles to be transferred from Box H to Box G
= 1 u - 11
= 16 - 11
= 5

Total number of pink and black marbles to be transferred from Box H to Box G
= 9 + 5
= 14

Answer(s): 14