PSLE
Charlie had orange staplers and purple staplers for sale. He sold 300 orange staplers. 40% of the staplers sold were purple.

1. How many orange staplers and purple staplers did Charlie sell altogether?
2. He sold 50% of his staplers. 60% of the staplers left unsold were orange. How many purple staplers did Charlie have at first?

	Orange	Purple	Total	Total in percent
Before	6 u	4 u	10 u	100%
Change	- 60% - 3 u	- 40% - 2 u	- 100% - 5 u	- 50%
After	60% 3 u	40% 2 u	100% 5 u	50%

40% = ⁴⁰₁₀₀ = ²₅

Total number of staplers sold = 5 u
Number of purple staplers sold = 2 u

Number of orange staplers sold
= 5 u - 2 u
= 3 u

3 u = 300

1 u = 300 ÷ 3 = 100

Total number of staplers sold
= 5 u
= 5 x 100
= 500

(b)
Percent of the staplers left unsold
= 100% - 50%
= 50%

50% of the staplers that were sold = 5 u
50% of the staplers that were left unsold = 5 u

Percent of the staplers left unsold that were orange = 60%
Percent of the staplers left unsold that were purple = 100% - 60% = 40%

Number of the staplers left unsold that were purple
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u
= 2 u

Number of purple staplers that Charlie had at first
= 2 u + 2 u
= 4 u
= 4 x 100
= 400

Answer(s): (a) 500; (b) 400