Container Q contains 6 green marbles and 10 grey marbles. Container R contains 41 green marbles and 13 grey marbles. How many grey marbles and green marbles must be moved from Container R to put into Container Q so that 50% of the marbles in Container A are green and 80% of the marbles in Container R are green?

	Container Q		Container R
	Green marbles	Grey marbles	Green marbles	Grey marbles
Before	6	10	41	13
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	4 p	1 p

50% = ⁵⁰₁₀₀ = 12

80% = ⁸⁰₁₀₀ = 45

Number of green marbles = 6 + 41 = 47 

Number of grey marbles = 10 + 13 = 23 

1 u + 4 p = 47 --- (1)

1 u + 1 p = 23 ---(2)

(1) - (2)
(1 u + 4 p) - (1 u + 1 p) = 47 - 23
4 p - 1 p = 24
3 p = 24

1 p = 24 ÷ 3 = 8

From (2):
1 u + 1 p = 23
1 u + 1 x 8 = 23
1 u + 8 = 23

1 u = 23 - 8 = 15

Number of grey marbles to be moved from Container R to Container Q
= 13 - 1 p
= 13 - 1 x 8
= 13 - 8
= 5

Number of green marbles to be moved from Container R to Container Q
= 1 u - 6
= 15 - 6
= 9

Total number of grey and green marbles to be moved from Container R to Container Q
= 5 + 9
= 14

Answer(s): 14