Container U contains 2 black marbles and 9 blue marbles. Container V contains 44 black marbles and 15 blue marbles. How many blue marbles and black marbles must be transferred from Container V to put into Container U so that 50% of the marbles in Container A are black and 75% of the marbles in Container V are black?

	Container U		Container V
	Black marbles	Blue marbles	Black marbles	Blue marbles
Before	2	9	44	15
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	3 p	1 p

50% = ⁵⁰₁₀₀ = 12

75% = ⁷⁵₁₀₀ = 34

Number of black marbles = 2 + 44 = 46 

Number of blue marbles = 9 + 15 = 24 

1 u + 3 p = 46 --- (1)

1 u + 1 p = 24 ---(2)

(1) - (2)
(1 u + 3 p) - (1 u + 1 p) = 46 - 24
3 p - 1 p = 22
2 p = 22

1 p = 22 ÷ 2 = 11

From (2):
1 u + 1 p = 24
1 u + 1 x 11 = 24
1 u + 11 = 24

1 u = 24 - 11 = 13

Number of blue marbles to be transferred from Container V to Container U
= 15 - 1 p
= 15 - 1 x 11
= 15 - 11
= 4

Number of black marbles to be transferred from Container V to Container U
= 1 u - 2
= 13 - 2
= 11

Total number of blue and black marbles to be transferred from Container V to Container U
= 4 + 11
= 15

Answer(s): 15