Ahmad, Paul and Seth had some erasers in the ratio of 2 : 3 : 5. Seth gave 40% of his erasers to Ahmad and Paul. As a result, Ahmad had the same number of erasers as Paul and Seth had 30 fewer erasers than Ahmad.

1. What was the percentage increase in Ahmad's erasers after receiving from Seth?
2. How many erasers did Paul have at first?

Ahmad	Paul	Seth	Total
2 u	3 u	5 u	10 u
+ 2 u		- 2 u
3.5 u	3.5 u	3 u	10 u

(a)
Number of erasers that Seth gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

Number of erasers that Ahmad and Paul each had in the end
= (10 u - 3 u) ÷ 2
= 7 u ÷ 2
= 3.5 u

Increase in the number of erasers that Ahmad had
= 3.5 u - 2 u
= 1.5 u

Percentage increase in Ahmad's erasers after receiving from Seth
= ^1.5₂ x 100%
= 75%

(b)
3.5 u = 3 u + 30
3.5 u - 3 u = 30
0.5 u = 30

1 u = 30 ÷ 0.5 = 60

Number of erasers that Paul had at first
= 3 u
= 3 x 60
= 180

Answer(s): (a) 75%; (b) 180