Fill in the blanks.
For (a) to (c), give the answers in units (Eg 1 u) or unit equations (Eg 1 u + 2).

Adam has some stickers.
He has 20 more blue stickers than green stickers.
He has 100 less red stickers than
the sum of the number of blue stickers and green stickers.

1. How many more red stickers than green stickers are there?
2. How many less red stickers than blue stickers are there?
3. How many blue and red stickers are there?

(a)
Choose the smallest group to be 1 u.

Number of green stickers = 1 u
Number of blue stickers = 1 u + 20

Number of green and blue stickers
= 1 u + 1 u + 20
= 2 u + 20

Number of red stickers
= 2 u + 20 - 100
= 2 u - 80

Number of red stickers more than green stickers
= (2 u - 80) - 1 u
= 2 u - 1 u - 80
= 1 u - 80

(b)
Number of red less than blue stickers
= (1 u + 20) - (2 u - 80)
= 1 u + 20 - 2 u + 80
= 20 + 80 + 1 u - 2 u
= 100 - 1 u

(c)
Number of blue and red stickers
= 1 u + 20 + 2 u - 80
= 1 u + 2 u + 20 - 80
= 3 u - 60

Answer(s): (a) 1 u - 80; (b) 100 - 1 u; (c) 3 u - 60