Crate V contains 12 silver marbles and 17 blue marbles. Crate W contains 24 silver marbles and 7 blue marbles. How many blue marbles and silver marbles must be moved from Crate W to put into Crate V so that 50% of the marbles in Crate A are silver and 80% of the marbles in Crate W are silver?

	Crate V		Crate W
	Silver marbles	Blue marbles	Silver marbles	Blue marbles
Before	12	17	24	7
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	4 p	1 p

50% = ⁵⁰₁₀₀ = 12

80% = ⁸⁰₁₀₀ = 45

Number of silver marbles = 12 + 24 = 36 

Number of blue marbles = 17 + 7 = 24 

1 u + 4 p = 36 --- (1)

1 u + 1 p = 24 ---(2)

(1) - (2)
(1 u + 4 p) - (1 u + 1 p) = 36 - 24
4 p - 1 p = 12
3 p = 12

1 p = 12 ÷ 3 = 4

From (2):
1 u + 1 p = 24
1 u + 1 x 4 = 24
1 u + 4 = 24

1 u = 24 - 4 = 20

Number of blue marbles to be moved from Crate W to Crate V
= 7 - 1 p
= 7 - 1 x 4
= 7 - 4
= 3

Number of silver marbles to be moved from Crate W to Crate V
= 1 u - 12
= 20 - 12
= 8

Total number of blue and silver marbles to be moved from Crate W to Crate V
= 3 + 8
= 11

Answer(s): 11