Box R contains 12 red beads and 5 silver beads. Box S contains 66 red beads and 25 silver beads. How many silver beads and red beads must be transferred from Box S to put into Box R so that 50% of the beads in Box A are red and 80% of the beads in Box S are red?

	Box R		Box S
	Red beads	Silver beads	Red beads	Silver beads
Before	12	5	66	25
Change	+ ?	+ ?	- ?	- ?
After	1 u	1 u	4 p	1 p

50% = ⁵⁰₁₀₀ = 12

80% = ⁸⁰₁₀₀ = 45

Number of red beads = 12 + 66 = 78 

Number of silver beads = 5 + 25 = 30 

1 u + 4 p = 78 --- (1)

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

(1) - (2)
(1 u + 4 p) - (1 u + 1 p) = 78 - 30
4 p - 1 p = 48
3 p = 48

1 p = 48 ÷ 3 = 16

From (2):
1 u + 1 p = 30
1 u + 1 x 16 = 30
1 u + 16 = 30

1 u = 30 - 16 = 14

Number of silver beads to be transferred from Box S to Box R
= 25 - 1 p
= 25 - 1 x 16
= 25 - 16
= 9

Number of red beads to be transferred from Box S to Box R
= 1 u - 12
= 14 - 12
= 2

Total number of silver and red beads to be transferred from Box S to Box R
= 9 + 2
= 11

Answer(s): 11