PSLE
Xavier had gold staplers and orange staplers for sale. He sold 60 gold staplers. 70% of the staplers sold were orange.

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

	Gold	Orange	Total	Total in percent
Before	10 u	10 u	20 u	100%
Change	- 30% - 3 u	- 70% - 7 u	- 100% - 10 u	- 50%
After	70% 7 u	30% 3 u	100% 10 u	50%

70% = ⁷⁰₁₀₀ = ⁷₁₀

Total number of staplers sold = 10 u
Number of orange staplers sold = 7 u

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

3 u = 60

1 u = 60 ÷ 3 = 20

Total number of staplers sold
= 10 u
= 10 x 20
= 200

(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 gold = 70%
Percent of the staplers left unsold that were orange = 100% - 70% = 30%

Number of the staplers left unsold that were orange
= 30% x 10 u
= ³⁰₁₀₀ x 10 u
= 3 u

Number of orange staplers that Xavier had at first
= 3 u + 7 u
= 10 u
= 10 x 20
= 200

Answer(s): (a) 200; (b) 200