PSLE
Fabian had yellow pencils and orange pencils for sale. He sold 20 yellow pencils. 60% of the pencils sold were orange.

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

	Yellow	Orange	Total	Total in percent
Before	5.75 u	4.25 u	10 u	100%
Change	- 40% - 2 u	- 60% - 3 u	- 100% - 5 u	- 50%
After	75% 3.75 u	25% 1.25 u	100% 5 u	50%

60% = ⁶⁰₁₀₀ = ³₅

Total number of pencils sold = 5 u
Number of orange pencils sold = 3 u

Number of yellow pencils sold
= 5 u - 3 u
= 2 u

2 u = 20

1 u = 20 ÷ 2 = 10

Total number of pencils sold
= 5 u
= 5 x 10
= 50

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

50% of the pencils that were sold = 5 u
50% of the pencils that were left unsold = 5 u

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

Number of the pencils left unsold that were orange
= 25% x 5 u
= ²⁵₁₀₀ x 5 u
= 1.25 u

Number of orange pencils that Fabian had at first
= 1.25 u + 3 u
= 4.25 u
= 4.25 x 10
= 42.5

Answer(s): (a) 50; (b) 42.5