Crate W contains 4 black beads and 8 yellow beads. Crate X contains 46 black beads and 22 yellow beads. How many yellow beads and black beads must be removed from Crate X to put into Crate W so that 50% of the beads in Crate A are black and 70% of the beads in Crate X are black?

	Crate W		Crate X
	Black beads	Yellow beads	Black beads	Yellow beads
Before	4	8	46	22
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	7 p	3 p

50% = ⁵⁰₁₀₀ = 12

70% = ⁷⁰₁₀₀ = 710

Number of black beads = 4 + 46 = 50 

Number of yellow beads = 8 + 22 = 30 

1 u + 7 p = 50 --- (1)

1 u + 3 p = 30 ---(2)

(1) - (2)
(1 u + 7 p) - (1 u + 3 p) = 50 - 30
7 p - 3 p = 20
4 p = 20

1 p = 20 ÷ 4 = 5

From (2):
1 u + 3 p = 30
1 u + 3 x 5 = 30
1 u + 15 = 30

1 u = 30 - 15 = 15

Number of yellow beads to be removed from Crate X to Crate W
= 22 - 3 p
= 22 - 3 x 5
= 22 - 15
= 7

Number of black beads to be removed from Crate X to Crate W
= 1 u - 4
= 15 - 4
= 11

Total number of yellow and black beads to be removed from Crate X to Crate W
= 7 + 11
= 18

Answer(s): 18