If 397 green stickers are added, 30% of the stickers will be red stickers.
If 162 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	7 u - 397	3 u	1 p	4 p - 162
Change	+ 397	No change	No change	+ 162
After	7 u	3 u	1 p	4 p

(a)
30% = ³⁰₁₀₀ = ³₁₀
20% = ²⁰₁₀₀ = ¹₅

Scenario 1
Fraction of the stickers that are green
= 1 - ³₁₀
= ⁷₁₀

Number of green stickers at first = 7 u - 397
Number of red stickers at first = 3 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 - 162

7 u - 397 = 1 p --- (1)

3 u = 4 p - 162
3 u + 162 = 4 p --- (2)

(1) _{x 4}
28 u - 1588 = 4 p --- (3)

(3) = (2)
28 u - 1588 = 3 u + 162
28 u - 3 u = 1588 + 162
25 u = 1750

1 u = 1750 ÷ 25 = 70

Number of green stickers
= 7 u - 397
= 7 x 70 - 397
= 490 - 397
= 93

(b)
Number of red stickers
= 3 u
= 3 x 70
= 210

Answer(s): (a) 93; (b) 210