PSLE
Albert had blue staplers and orange staplers for sale. He sold 560 blue staplers. 30% of the staplers sold were orange.

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

	Blue	Orange	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 orange staplers sold = 3 u

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

7 u = 560

1 u = 560 ÷ 7 = 80

Total number of staplers sold
= 10 u
= 10 x 80
= 800

(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 blue = 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 Albert had at first
= 3 u + 3 u
= 6 u
= 6 x 80
= 480

Answer(s): (a) 800; (b) 480