There are 25% more red stamps than pink stamps in a bag. After Seth removed 20% of the red stamps and increased the number of pink stamps by 20%, there are now 72 fewer red stamps than pink stamps. Find the number of pink stamps at first.

	Red	Pink
Before	5 u	4 u
Change	- 1 u	+ 0.8 u
After	4 u	4.8 u

Number of red stamps in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄

Number of red stamps that Seth removed
= 20% x 5 u
= ²⁰₁₀₀ x 5 u 
= 1 u

Number of pink stamps that Seth increased 
= 20% x 4 u
= ²⁰₁₀₀  x 4 u
= 0.8 u

Number of red stamps in the end
= 5 u - 1 u
= 4 u

Number of pink stamps in the end
= 4 u + 0.8 u
= 4.8 u

Number of fewer red stamps than pink stamps in the end
= 4.8 u - 4 u 
= 0.8 u 

0.8 u = 72

1 u = 72 ÷ 0.8 = 90

Number of pink stamps at first
= 4 u
= 4 x 90
= 360

Answer(s): 360