There are 25% more pink marbles than brown marbles in a bag. After Archie removed 40% of the pink marbles and increased the number of brown marbles by 20%, there are now 54 fewer pink marbles than brown marbles. Find the number of brown marbles at first.

	Pink	Brown
Before	5 u	4 u
Change	- 2 u	+ 0.8 u
After	3 u	4.8 u

Number of pink marbles in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄

Number of pink marbles that Archie removed
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u 
= 2 u

Number of brown marbles that Archie increased 
= 20% x 4 u
= ²⁰₁₀₀  x 4 u
= 0.8 u

Number of pink marbles in the end
= 5 u - 2 u
= 3 u

Number of brown marbles in the end
= 4 u + 0.8 u
= 4.8 u

Number of fewer pink marbles than brown marbles in the end
= 4.8 u - 3 u 
= 1.8 u 

1.8 u = 54

1 u = 54 ÷ 1.8 = 30

Number of brown marbles at first
= 4 u
= 4 x 30
= 120

Answer(s): 120