Oscar, Tim and George had some erasers in the ratio of 2 : 3 : 5. George gave 40% of his erasers to Oscar and Tim. As a result, Oscar had the same number of erasers as Tim and George had 36 fewer erasers than Oscar.

1. What was the percentage increase in Oscar's erasers after receiving from George?
2. How many erasers did Tim have at first?

Oscar	Tim	George	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 George gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

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

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

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

(b)
3.5 u = 3 u + 36
3.5 u - 3 u = 36
0.5 u = 36

1 u = 36 ÷ 0.5 = 72

Number of erasers that Tim had at first
= 3 u
= 3 x 72
= 216

Answer(s): (a) 75%; (b) 216