Container K contains 9 red marbles and 12 brown marbles. Container L contains 58 red marbles and 16 brown marbles. How many brown marbles and red marbles must be moved from Container L to put into Container K so that 50% of the marbles in Container A are red and 80% of the marbles in Container L are red?

	Container K		Container L
	Red marbles	Brown marbles	Red marbles	Brown marbles
Before	9	12	58	16
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	4 p	1 p

50% = ⁵⁰₁₀₀ = 12

80% = ⁸⁰₁₀₀ = 45

Number of red marbles = 9 + 58 = 67 

Number of brown marbles = 12 + 16 = 28 

1 u + 4 p = 67 --- (1)

1 u + 1 p = 28 ---(2)

(1) - (2)
(1 u + 4 p) - (1 u + 1 p) = 67 - 28
4 p - 1 p = 39
3 p = 39

1 p = 39 ÷ 3 = 13

From (2):
1 u + 1 p = 28
1 u + 1 x 13 = 28
1 u + 13 = 28

1 u = 28 - 13 = 15

Number of brown marbles to be moved from Container L to Container K
= 16 - 1 p
= 16 - 1 x 13
= 16 - 13
= 3

Number of red marbles to be moved from Container L to Container K
= 1 u - 9
= 15 - 9
= 6

Total number of brown and red marbles to be moved from Container L to Container K
= 3 + 6
= 9

Answer(s): 9