PSLE
Jeremy had red pencils and orange pencils for sale. He sold 360 red pencils. 70% of the pencils sold were orange.

1. How many red pencils and orange pencils did Jeremy sell altogether?
2. He sold 50% of his pencils. 75% of the pencils left unsold were red. How many orange pencils did Jeremy have at first?

	Red	Orange	Total	Total in percent
Before	10.5 u	9.5 u	20 u	100%
Change	- 30% - 3 u	- 70% - 7 u	- 100% - 10 u	- 50%
After	75% 7.5 u	25% 2.5 u	100% 10 u	50%

70% = ⁷⁰₁₀₀ = ⁷₁₀

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

Number of red pencils sold
= 10 u - 7 u
= 3 u

3 u = 360

1 u = 360 ÷ 3 = 120

Total number of pencils sold
= 10 u
= 10 x 120
= 1200

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

50% of the pencils that were sold = 10 u
50% of the pencils that were left unsold = 10 u

Percent of the pencils left unsold that were red = 75%
Percent of the pencils left unsold that were orange = 100% - 75% = 25%

Number of the pencils left unsold that were orange
= 25% x 10 u
= ²⁵₁₀₀ x 10 u
= 2.5 u

Number of orange pencils that Jeremy had at first
= 2.5 u + 7 u
= 9.5 u
= 9.5 x 120
= 1140

Answer(s): (a) 1200; (b) 1140