There are 25% more yellow cards than brown cards in a bag. After Riordan removed 40% of the yellow cards and increased the number of brown cards by 30%, there are now 176 fewer yellow cards than brown cards. Find the number of brown cards at first.

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

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

125% = ¹²⁵₁₀₀ = ⁵₄

Number of yellow cards that Riordan removed
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u 
= 2 u

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

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

2.2 u = 176

1 u = 176 ÷ 2.2 = 80

Number of brown cards at first
= 4 u
= 4 x 80
= 320

Answer(s): 320