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 green stickers than red stickers.
He has 60 less blue stickers than
the sum of the number of green stickers and red stickers.

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

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

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

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

Number of blue stickers
= 2 u + 20 - 60
= 2 u - 40

Number of blue stickers more than red stickers
= (2 u - 40) - 1 u
= 2 u - 1 u - 40
= 1 u - 40

(b)
Number of blue less than green stickers
= (1 u + 20) - (2 u - 40)
= 1 u + 20 - 2 u + 40
= 20 + 40 + 1 u - 2 u
= 60 - 1 u

(c)
Number of green and blue stickers
= 1 u + 20 + 2 u - 40
= 1 u + 2 u + 20 - 40
= 3 u - 20

Answer(s): (a) 1 u - 40; (b) 60 - 1 u; (c) 3 u - 20