Container X contains 4 yellow balls and 2 purple balls. Container Y contains 49 yellow balls and 23 purple balls. How many purple balls and yellow balls must be moved from Container Y to put into Container X so that 50% of the balls in Container A are yellow and 75% of the balls in Container Y are yellow?

	Container X		Container Y
	Yellow balls	Purple balls	Yellow balls	Purple balls
Before	4	2	49	23
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	3 p	1 p

50% = ⁵⁰₁₀₀ = 12

75% = ⁷⁵₁₀₀ = 34

Number of yellow balls = 4 + 49 = 53 

Number of purple balls = 2 + 23 = 25 

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

1 u + 1 p = 25 ---(2)

(1) - (2)
(1 u + 3 p) - (1 u + 1 p) = 53 - 25
3 p - 1 p = 28
2 p = 28

1 p = 28 ÷ 2 = 14

From (2):
1 u + 1 p = 25
1 u + 1 x 14 = 25
1 u + 14 = 25

1 u = 25 - 14 = 11

Number of purple balls to be moved from Container Y to Container X
= 23 - 1 p
= 23 - 1 x 14
= 23 - 14
= 9

Number of yellow balls to be moved from Container Y to Container X
= 1 u - 4
= 11 - 4
= 7

Total number of purple and yellow balls to be moved from Container Y to Container X
= 9 + 7
= 16

Answer(s): 16