PSLE
Michael had silver staplers and purple staplers for sale. He sold 350 silver staplers. 30% of the staplers sold were purple.

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

	Silver	Purple	Total	Total in percent
Before	14 u	6 u	20 u	100%
Change	- 70% - 7 u	- 30% - 3 u	- 100% - 10 u	- 50%
After	70% 7 u	30% 3 u	100% 10 u	50%

30% = ³⁰₁₀₀ = ³₁₀

Total number of staplers sold = 10 u
Number of purple staplers sold = 3 u

Number of silver staplers sold
= 10 u - 3 u
= 7 u

7 u = 350

1 u = 350 ÷ 7 = 50

Total number of staplers sold
= 10 u
= 10 x 50
= 500

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

50% of the staplers that were sold = 10 u
50% of the staplers that were left unsold = 10 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 10 u
= ³⁰₁₀₀ x 10 u
= 3 u

Number of purple staplers that Michael had at first
= 3 u + 3 u
= 6 u
= 6 x 50
= 300

Answer(s): (a) 500; (b) 300