Adam spends $15.50 on 4 stickers and 5 marbles.
A sticker costs $1.40 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 + 1.40
Total cost of 4 stickers and 5 marbles
= 4(1 u + 1.40) + 5 u
= 4 u + 5.60 + 5 u
= 4 u + 5 u + 5.60
= 9 u + 5.60
9 u + 5.60 = 15.50
9 u = 15.50 - 5.60
9 u = 9.90
1 u = 9.90 ÷ 9 = 1.10
Cost of 1 sticker
= 1 u + 1.40
= 1.10 + 1.40
= $2.50
(b)
Cost of 7 stickers
= 7 x 2.50
= $17.50
(c)
Cost of 1 marble and 7 stickers
= 1.10 + 17.50
= $18.60
(d)
Cost of 7 stickers more than 1 marble
= 17.50 - 1.10
= $16.40
Answer(s): (a) $2.50; (b) $17.50; (c) $18.60; (d) $16.40