If 140 green stickers are added, 40% of the stickers will be red stickers.
If 220 red stickers are added, 20% of the stickers will be green stickers.

1. How many green stickers are there? 
2. How many red stickers are there? 

	Scenario 1		Scenario 2
	Green	Red	Green	Red
Before	3 u - 140	2 u	1 p	4 p - 220
Change	+ 140	No change	No change	+ 220
After	3 u	2 u	1 p	4 p

(a)
40% = ⁴⁰₁₀₀ = ²₅
20% = ²⁰₁₀₀ = ¹₅

Scenario 1
Fraction of the stickers that are green
= 1 - ²₅
= ³₅

Number of green stickers at first = 3 u - 140
Number of red stickers at first = 2 u

Scenario 2
Fraction of the stickers that are red
= 1 - ¹₅
= ⁴₅

Number of green stickers at first = 1 p
Number of red stickers at first = 4 p - 220

3 u - 140 = 1 p --- (1)

2 u = 4 p - 220
2 u + 220 = 4 p --- (2)

(1) _{x 4}
12 u - 560 = 4 p --- (3)

(3) = (2)
12 u - 560 = 2 u + 220
12 u - 2 u = 560 + 220
10 u = 780

1 u = 780 ÷ 10 = 78

Number of green stickers
= 3 u - 140
= 3 x 78 - 140
= 234 - 140
= 94

(b)
Number of red stickers
= 2 u
= 2 x 78
= 156

Answer(s): (a) 94; (b) 156