Adam has 200 stickers.
He has 20 less red stickers than blue stickers.
He has 30 less green stickers than red stickers.
How many less green stickers than blue and red stickers does Adam have?
Choose the smallest group to be 1 u.

Number of green stickers = 1 u
Number of red stickers = 1 u + 30
Number of blue stickers = 1 u + 30 + 20 = 1 u + 50

Total number of stickers
= 1 u + 1 u + 30 + 1 u + 50
= 3 u + 80

3 u + 80 = 200
3 u = 200 - 80
3 u = 120

1 u = 120 ÷ 3 = 40

Total number of blue and red stickers
= 1 u + 30 + 1 u + 50
= 2 u + 80

Number of less green stickers than blue and red stickers
= 2 u + 80 - 1 u
= 2 u - 1 u + 80
= 1 u + 80
= 40 + 80
= 120

Answer(s): 120