There were some gold stamps and pink stamps. The stamps were packed into 2 bags. At first, Bag A contained 110 stamps and 40% of them were pink stamps. Bag B contained 210 stamps and 60% of them were pink stamps. How many gold stamps and pink stamps in total must be moved from Bag A to Bag B such that 30% of the stamps in Bag A are gold and 50% of the stamps in Bag B are pink?

	Bag A		Bag B
Total	110		210
	Pink stamps	Gold stamps	Pink stamps	Gold stamps
Before	44	66	126	84
Change	- ?	- ?	+ ?	+ ?
After	7 u	3 u	1 p	1 p

Number of pink stamps in Bag A at first
= 40% x 110
= ⁴⁰₁₀₀ x 110
= 44

Number of gold stamps in Bag A at first
= 110 - 44
= 66

Number of pink stamps in Bag B at first
= 60% x 210
= ⁶⁰₁₀₀ x 210
= 126

Number of gold stamps in Bag B at first
= 210 - 126
= 84

Bag A in the end
30% = ³⁰₁₀₀ =³₁₀
Pink stamps : Gold stamps = 7 : 3

Bag B in the end
50% = ⁵⁰₁₀₀ =¹₂
Pink stamps : Gold stamps = 1 : 1

Total number of pink stamps = 7 u + 1 p

7 u + 1 p = 44 + 126
7 u + 1 p = 170 

1 p = 170 - 7 u --- (1)

Total number of gold stamps = 3 u + 1 p
3 u + 1 p = 66 + 84
3 u + 1 p = 150

1 p = 150 - 3 u --- (2)

(2) = (1)
150 - 3 u = 170 - 7 u
7 u - 3 u = 170 - 150
4 u = 20

1 u = 20 ÷ 4 = 5

Total number of gold stamps and pink stamps that must be moved from Bag A to Bag B
= 110 - 10 u
= 110 - 10 x 5
= 110 - 50
= 60

Answer(s): 60