Container E contains 7 brown marbles and 10 black marbles. Container F contains 46 brown marbles and 17 black marbles. How many black marbles and brown marbles must be moved from Container F to put into Container E so that 50% of the marbles in Container A are brown and 75% of the marbles in Container F are brown?

	Container E		Container F
	Brown marbles	Black marbles	Brown marbles	Black marbles
Before	7	10	46	17
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	3 p	1 p

50% = ⁵⁰₁₀₀ = 12

75% = ⁷⁵₁₀₀ = 34

Number of brown marbles = 7 + 46 = 53 

Number of black marbles = 10 + 17 = 27 

1 u + 3 p = 53 --- (1)

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

(1) - (2)
(1 u + 3 p) - (1 u + 1 p) = 53 - 27
3 p - 1 p = 26
2 p = 26

1 p = 26 ÷ 2 = 13

From (2):
1 u + 1 p = 27
1 u + 1 x 13 = 27
1 u + 13 = 27

1 u = 27 - 13 = 14

Number of black marbles to be moved from Container F to Container E
= 17 - 1 p
= 17 - 1 x 13
= 17 - 13
= 4

Number of brown marbles to be moved from Container F to Container E
= 1 u - 7
= 14 - 7
= 7

Total number of black and brown marbles to be moved from Container F to Container E
= 4 + 7
= 11

Answer(s): 11