There were some brown stamps and pink stamps. The stamps were packed into 2 bags. At first, Packet T contained 150 stamps and 10% of them were pink stamps. Packet U contained 640 stamps and 60% of them were pink stamps. How many brown stamps and pink stamps in total must be moved from Packet T to Packet U such that 25% of the stamps in Packet T are brown and 50% of the stamps in Packet U are pink?

	Packet T		Packet U
Total	150		640
	Pink stamps	Brown stamps	Pink stamps	Brown stamps
Before	15	135	384	256
Change	- ?	- ?	+ ?	+ ?
After	3 u	1 u	1 p	1 p

Number of pink stamps in Packet T at first
= 10% x 150
= ¹⁰₁₀₀ x 150
= 15

Number of brown stamps in Packet T at first
= 150 - 15
= 135

Number of pink stamps in Packet U at first
= 60% x 640
= ⁶⁰₁₀₀ x 640
= 384

Number of brown stamps in Packet U at first
= 640 - 384
= 256

Packet T in the end
25% = ²⁵₁₀₀ =¹₄
Pink stamps : Brown stamps = 3 : 1

Packet U in the end
50% = ⁵⁰₁₀₀ =¹₂
Pink stamps : Brown stamps = 1 : 1

Total number of pink stamps = 3 u + 1 p

3 u + 1 p = 15 + 384
3 u + 1 p = 399 

1 p = 399 - 3 u --- (1)

Total number of brown stamps = 1 u + 1 p
1 u + 1 p = 135 + 256
1 u + 1 p = 391

1 p = 391 - 1 u --- (2)

(2) = (1)
391 - 1 u = 399 - 3 u
3 u - 1 u = 399 - 391
2 u = 8

1 u = 8 ÷ 2 = 4

Total number of brown stamps and pink stamps that must be moved from Packet T to Packet U
= 150 - 4 u
= 150 - 4 x 4
= 150 - 16
= 134

Answer(s): 134