Justin, Simon and Reggie had some erasers in the ratio of 2 : 3 : 5. Reggie gave 40% of his erasers to Justin and Simon. As a result, Justin had the same number of erasers as Simon and Reggie had 15 fewer erasers than Justin.

1. What was the percentage increase in Justin's erasers after receiving from Reggie?
2. How many erasers did Simon have at first?

Justin	Simon	Reggie	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 Reggie gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

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

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

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

(b)
3.5 u = 3 u + 15
3.5 u - 3 u = 15
0.5 u = 15

1 u = 15 ÷ 0.5 = 30

Number of erasers that Simon had at first
= 3 u
= 3 x 30
= 90

Answer(s): (a) 75%; (b) 90