There are 25% more green marbles than yellow marbles in a bag. After Harry removed 20% of the green marbles and increased the number of yellow marbles by 10%, there are now 32 fewer green marbles than yellow marbles. Find the number of yellow marbles at first.

	Green	Yellow
Before	5 u	4 u
Change	- 1 u	+ 0.4 u
After	4 u	4.4 u

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

125% = ¹²⁵₁₀₀ = ⁵₄

Number of green marbles that Harry removed
= 20% x 5 u
= ²⁰₁₀₀ x 5 u 
= 1 u

Number of yellow marbles that Harry increased 
= 10% x 4 u
= ¹⁰₁₀₀  x 4 u
= 0.4 u

Number of green marbles in the end
= 5 u - 1 u
= 4 u

Number of yellow marbles in the end
= 4 u + 0.4 u
= 4.4 u

Number of fewer green marbles than yellow marbles in the end
= 4.4 u - 4 u 
= 0.4 u 

0.4 u = 32

1 u = 32 ÷ 0.4 = 80

Number of yellow marbles at first
= 4 u
= 4 x 80
= 320

Answer(s): 320