There were some red coins and blue coins. The coins were packed into 2 bags. At first, Box K contained 125 coins and 40% of them were blue coins. Box L contained 245 coins and 60% of them were blue coins. How many red coins and blue coins in total must be moved from Box K to Box L such that 25% of the coins in Box K are red and 50% of the coins in Box L are blue?

	Box K		Box L
Total	125		245
	Blue coins	Red coins	Blue coins	Red coins
Before	50	75	147	98
Change	- ?	- ?	+ ?	+ ?
After	3 u	1 u	1 p	1 p

Number of blue coins in Box K at first
= 40% x 125
= ⁴⁰₁₀₀ x 125
= 50

Number of red coins in Box K at first
= 125 - 50
= 75

Number of blue coins in Box L at first
= 60% x 245
= ⁶⁰₁₀₀ x 245
= 147

Number of red coins in Box L at first
= 245 - 147
= 98

Box K in the end
25% = ²⁵₁₀₀ =¹₄
Blue coins : Red coins = 3 : 1

Box L in the end
50% = ⁵⁰₁₀₀ =¹₂
Blue coins : Red coins = 1 : 1

Total number of blue coins = 3 u + 1 p

3 u + 1 p = 50 + 147
3 u + 1 p = 197 

1 p = 197 - 3 u --- (1)

Total number of red coins = 1 u + 1 p
1 u + 1 p = 75 + 98
1 u + 1 p = 173

1 p = 173 - 1 u --- (2)

(2) = (1)
173 - 1 u = 197 - 3 u
3 u - 1 u = 197 - 173
2 u = 24

1 u = 24 ÷ 2 = 12

Total number of red coins and blue coins that must be moved from Box K to Box L
= 125 - 4 u
= 125 - 4 x 12
= 125 - 48
= 77

Answer(s): 77