PSLE
Cole had green markers and yellow markers for sale. He sold 630 green markers. 30% of the markers sold were yellow.

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

	Green	Yellow	Total	Total in percent
Before	14.5 u	5.5 u	20 u	100%
Change	- 70% - 7 u	- 30% - 3 u	- 100% - 10 u	- 50%
After	75% 7.5 u	25% 2.5 u	100% 10 u	50%

30% = ³⁰₁₀₀ = ³₁₀

Total number of markers sold = 10 u
Number of yellow markers sold = 3 u

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

7 u = 630

1 u = 630 ÷ 7 = 90

Total number of markers sold
= 10 u
= 10 x 90
= 900

(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 green = 75%
Percent of the markers left unsold that were yellow = 100% - 75% = 25%

Number of the markers left unsold that were yellow
= 25% x 10 u
= ²⁵₁₀₀ x 10 u
= 2.5 u

Number of yellow markers that Cole had at first
= 2.5 u + 3 u
= 5.5 u
= 5.5 x 90
= 495

Answer(s): (a) 900; (b) 495