Container N contains 4 silver marbles and 3 blue marbles. Container P contains 61 silver marbles and 30 blue marbles. How many blue marbles and silver marbles must be transferred from Container P to put into Container N so that 50% of the marbles in Container A are silver and 70% of the marbles in Container P are silver?

	Container N		Container P
	Silver marbles	Blue marbles	Silver marbles	Blue marbles
Before	4	3	61	30
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	7 p	3 p

50% = ⁵⁰₁₀₀ = 12

70% = ⁷⁰₁₀₀ = 710

Number of silver marbles = 4 + 61 = 65 

Number of blue marbles = 3 + 30 = 33 

1 u + 7 p = 65 --- (1)

1 u + 3 p = 33 ---(2)

(1) - (2)
(1 u + 7 p) - (1 u + 3 p) = 65 - 33
7 p - 3 p = 32
4 p = 32

1 p = 32 ÷ 4 = 8

From (2):
1 u + 3 p = 33
1 u + 3 x 8 = 33
1 u + 24 = 33

1 u = 33 - 24 = 9

Number of blue marbles to be transferred from Container P to Container N
= 30 - 3 p
= 30 - 3 x 8
= 30 - 24
= 6

Number of silver marbles to be transferred from Container P to Container N
= 1 u - 4
= 9 - 4
= 5

Total number of blue and silver marbles to be transferred from Container P to Container N
= 6 + 5
= 11

Answer(s): 11