Adam spends $15.30 on 4 stickers and 5 marbles.
A sticker costs $1.80 more than 1 marble.
- How much does 1 sticker cost?
- How much do 6 stickers cost?
- How much do a marble and 6 stickers cost?
- How much do 6 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 + 1.80
Total cost of 4 stickers and 5 marbles
= 4(1 u + 1.80) + 5 u
= 4 u + 7.20 + 5 u
= 4 u + 5 u + 7.20
= 9 u + 7.20
9 u + 7.20 = 15.30
9 u = 15.30 - 7.20
9 u = 8.10
1 u = 8.10 ÷ 9 = 0.90
Cost of 1 sticker
= 1 u + 1.80
= 0.90 + 1.80
= $2.70
(b)
Cost of 6 stickers
= 6 x 2.70
= $16.20
(c)
Cost of 1 marble and 6 stickers
= 0.90 + 16.20
= $17.10
(d)
Cost of 6 stickers more than 1 marble
= 16.20 - 0.90
= $15.30
Answer(s): (a) $2.70; (b) $16.20; (c) $17.10; (d) $15.30