PSLE
Ian had purple markers and orange markers for sale. He sold 330 purple markers. 70% of the markers sold were orange.

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

	Purple	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 markers sold = 10 u
Number of orange markers sold = 7 u

Number of purple markers sold
= 10 u - 7 u
= 3 u

3 u = 330

1 u = 330 ÷ 3 = 110

Total number of markers sold
= 10 u
= 10 x 110
= 1100

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

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

Percent of the markers left unsold that were purple = 70%
Percent of the markers left unsold that were orange = 100% - 70% = 30%

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

Number of orange markers that Ian had at first
= 3 u + 7 u
= 10 u
= 10 x 110
= 1100

Answer(s): (a) 1100; (b) 1100