PSLE
Ryan had silver staplers and purple staplers for sale. He sold 60 silver staplers. 40% of the staplers sold were purple.

1. How many silver staplers and purple staplers did Ryan sell altogether?
2. He sold 50% of his staplers. 70% of the staplers left unsold were silver. How many purple staplers did Ryan have at first?

	Silver	Purple	Total	Total in percent
Before	6.5 u	3.5 u	10 u	100%
Change	- 60% - 3 u	- 40% - 2 u	- 100% - 5 u	- 50%
After	70% 3.5 u	30% 1.5 u	100% 5 u	50%

40% = ⁴⁰₁₀₀ = ²₅

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

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

3 u = 60

1 u = 60 ÷ 3 = 20

Total number of staplers sold
= 5 u
= 5 x 20
= 100

(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 silver = 70%
Percent of the staplers left unsold that were purple = 100% - 70% = 30%

Number of the staplers left unsold that were purple
= 30% x 5 u
= ³⁰₁₀₀ x 5 u
= 1.5 u

Number of purple staplers that Ryan had at first
= 1.5 u + 2 u
= 3.5 u
= 3.5 x 20
= 70

Answer(s): (a) 100; (b) 70