There are 25% more green stickers than blue stickers in a bag. After Warren removed 40% of the green stickers and increased the number of blue stickers by 20%, there are now 90 fewer green stickers than blue stickers. Find the number of blue stickers at first.

	Green	Blue
Before	5 u	4 u
Change	- 2 u	+ 0.8 u
After	3 u	4.8 u

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

125% = ¹²⁵₁₀₀ = ⁵₄

Number of green stickers that Warren removed
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u 
= 2 u

Number of blue stickers that Warren increased 
= 20% x 4 u
= ²⁰₁₀₀  x 4 u
= 0.8 u

Number of green stickers in the end
= 5 u - 2 u
= 3 u

Number of blue stickers in the end
= 4 u + 0.8 u
= 4.8 u

Number of fewer green stickers than blue stickers in the end
= 4.8 u - 3 u 
= 1.8 u 

1.8 u = 90

1 u = 90 ÷ 1.8 = 50

Number of blue stickers at first
= 4 u
= 4 x 50
= 200

Answer(s): 200