Reggie, Zane and Charlie had some erasers in the ratio of 2 : 3 : 5. Charlie gave 50% of his erasers to Reggie and Zane. As a result, Reggie had the same number of erasers as Zane and Charlie had 15 fewer erasers than Reggie.

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

Reggie	Zane	Charlie	Total
2 u	3 u	5 u	10 u
+ 2.5 u		- 2.5 u
3.75 u	3.75 u	2.5 u	10 u

(a)
Number of erasers that Charlie gave away
= 50% x 5
= ⁵⁰₁₀₀ x 5
= 2.5 u

Number of erasers that Reggie and Zane each had in the end
= (10 u - 2.5 u) ÷ 2
= 7.5 u ÷ 2
= 3.75 u

Increase in the number of erasers that Reggie had
= 3.75 u - 2 u
= 1.75 u

Percentage increase in Reggie's erasers after receiving from Charlie
= ^1.75₂ x 100%
= 87.5%

(b)
3.75 u = 2.5 u + 15
3.75 u - 2.5 u = 15
1.25 u = 15

1 u = 15 ÷ 1.25 = 12

Number of erasers that Zane had at first
= 3 u
= 3 x 12
= 36

Answer(s): (a) 87.5%; (b) 36