Adam spends $15.70 on 3 stickers and 4 marbles.
A sticker costs $1.50 more than 1 marble.
- How much does 1 sticker cost?
- How much do 7 stickers cost?
- How much do a marble and 7 stickers cost?
- How much do 7 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 + 1.50
Total cost of 3 stickers and 4 marbles
= 3(1 u + 1.50) + 4 u
= 3 u + 4.50 + 4 u
= 3 u + 4 u + 4.50
= 7 u + 4.50
7 u + 4.50 = 15.70
7 u = 15.70 - 4.50
7 u = 11.20
1 u = 11.20 ÷ 7 = 1.60
Cost of 1 sticker
= 1 u + 1.50
= 1.60 + 1.50
= $3.10
(b)
Cost of 7 stickers
= 7 x 3.10
= $21.70
(c)
Cost of 1 marble and 7 stickers
= 1.60 + 21.70
= $23.30
(d)
Cost of 7 stickers more than 1 marble
= 21.70 - 1.60
= $20.10
Answer(s): (a) $3.10; (b) $21.70; (c) $23.30; (d) $20.10