There are 25% more white cards than brown cards in a bag. After Charlie removed 40% of the white cards and increased the number of brown cards by 30%, there are now 88 fewer white cards than brown cards. Find the number of brown cards at first.

	White	Brown
Before	5 u	4 u
Change	- 2 u	+ 1.2 u
After	3 u	5.2 u

Number of white cards in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄

Number of white cards that Charlie removed
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u 
= 2 u

Number of brown cards that Charlie increased 
= 30% x 4 u
= ³⁰₁₀₀  x 4 u
= 1.2 u

Number of white cards in the end
= 5 u - 2 u
= 3 u

Number of brown cards in the end
= 4 u + 1.2 u
= 5.2 u

Number of fewer white cards than brown cards in the end
= 5.2 u - 3 u 
= 2.2 u 

2.2 u = 88

1 u = 88 ÷ 2.2 = 40

Number of brown cards at first
= 4 u
= 4 x 40
= 160

Answer(s): 160