Adam spends $12.90 on 3 stickers and 4 marbles.
A sticker costs $2.20 more than 1 marble.
- How much does 1 sticker cost?
- How much do 4 stickers cost?
- How much do a marble and 4 stickers cost?
- How much do 4 stickers cost more than 1 marble?
(a)
Let the cheaper item be 1 u.
Cost of 1 marble = 1 u
Cost of 1 sticker = 1 u + 2.20
Total cost of 3 stickers and 4 marbles
= 3(1 u + 2.20) + 4 u
= 3 u + 6.60 + 4 u
= 3 u + 4 u + 6.60
= 7 u + 6.60
7 u + 6.60 = 12.90
7 u = 12.90 - 6.60
7 u = 6.30
1 u = 6.30 ÷ 7 = 0.90
Cost of 1 sticker
= 1 u + 2.20
= 0.90 + 2.20
= $3.10
(b)
Cost of 4 stickers
= 4 x 3.10
= $12.40
(c)
Cost of 1 marble and 4 stickers
= 0.90 + 12.40
= $13.30
(d)
Cost of 4 stickers more than 1 marble
= 12.40 - 0.90
= $11.50
Answer(s): (a) $3.10; (b) $12.40; (c) $13.30; (d) $11.50