Box X contains 6 green beads and 14 black beads. Box Y contains 24 green beads and 7 black beads. How many black beads and green beads must be moved from Box Y to put into Box X so that 50% of the beads in Box A are green and 80% of the beads in Box Y are green?

	Box X		Box Y
	Green beads	Black beads	Green beads	Black beads
Before	6	14	24	7
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	4 p	1 p

50% = ⁵⁰₁₀₀ = 12

80% = ⁸⁰₁₀₀ = 45

Number of green beads = 6 + 24 = 30 

Number of black beads = 14 + 7 = 21 

1 u + 4 p = 30 --- (1)

1 u + 1 p = 21 ---(2)

(1) - (2)
(1 u + 4 p) - (1 u + 1 p) = 30 - 21
4 p - 1 p = 9
3 p = 9

1 p = 9 ÷ 3 = 3

From (2):
1 u + 1 p = 21
1 u + 1 x 3 = 21
1 u + 3 = 21

1 u = 21 - 3 = 18

Number of black beads to be moved from Box Y to Box X
= 7 - 1 p
= 7 - 1 x 3
= 7 - 3
= 4

Number of green beads to be moved from Box Y to Box X
= 1 u - 6
= 18 - 6
= 12

Total number of black and green beads to be moved from Box Y to Box X
= 4 + 12
= 16

Answer(s): 16