There are 25% more brown stickers than black stickers in a bag. After Valen removed 20% of the brown stickers and increased the number of black stickers by 30%, there are now 132 fewer brown stickers than black stickers. Find the number of black stickers at first.

	Brown	Black
Before	5 u	4 u
Change	- 1 u	+ 1.2 u
After	4 u	5.2 u

Number of brown stickers in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄

Number of brown stickers that Valen removed
= 20% x 5 u
= ²⁰₁₀₀ x 5 u 
= 1 u

Number of black stickers that Valen increased 
= 30% x 4 u
= ³⁰₁₀₀  x 4 u
= 1.2 u

Number of brown stickers in the end
= 5 u - 1 u
= 4 u

Number of black stickers in the end
= 4 u + 1.2 u
= 5.2 u

Number of fewer brown stickers than black stickers in the end
= 5.2 u - 4 u 
= 1.2 u 

1.2 u = 132

1 u = 132 ÷ 1.2 = 110

Number of black stickers at first
= 4 u
= 4 x 110
= 440

Answer(s): 440