PSLE
Howard had yellow notebooks and pink notebooks for sale. He sold 200 yellow notebooks. 60% of the notebooks sold were pink.

1. How many yellow notebooks and pink notebooks did Howard sell altogether?
2. He sold 50% of his notebooks. 60% of the notebooks left unsold were yellow. How many pink notebooks did Howard have at first?

	Yellow	Pink	Total	Total in percent
Before	5 u	5 u	10 u	100%
Change	- 40% - 2 u	- 60% - 3 u	- 100% - 5 u	- 50%
After	60% 3 u	40% 2 u	100% 5 u	50%

60% = ⁶⁰₁₀₀ = ³₅

Total number of notebooks sold = 5 u
Number of pink notebooks sold = 3 u

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

2 u = 200

1 u = 200 ÷ 2 = 100

Total number of notebooks sold
= 5 u
= 5 x 100
= 500

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

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

Percent of the notebooks left unsold that were yellow = 60%
Percent of the notebooks left unsold that were pink = 100% - 60% = 40%

Number of the notebooks left unsold that were pink
= 40% x 5 u
= ⁴⁰₁₀₀ x 5 u
= 2 u

Number of pink notebooks that Howard had at first
= 2 u + 3 u
= 5 u
= 5 x 100
= 500

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