There are 25% more purple marbles than silver marbles in a bag. After Nick removed 40% of the purple marbles and increased the number of silver marbles by 10%, there are now 70 fewer purple marbles than silver marbles. Find the number of silver marbles at first.

	Purple	Silver
Before	5 u	4 u
Change	- 2 u	+ 0.4 u
After	3 u	4.4 u

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

125% = ¹²⁵₁₀₀ = ⁵₄

Number of purple marbles that Nick removed
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u 
= 2 u

Number of silver marbles that Nick increased 
= 10% x 4 u
= ¹⁰₁₀₀  x 4 u
= 0.4 u

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

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

Number of fewer purple marbles than silver marbles in the end
= 4.4 u - 3 u 
= 1.4 u 

1.4 u = 70

1 u = 70 ÷ 1.4 = 50

Number of silver marbles at first
= 4 u
= 4 x 50
= 200

Answer(s): 200