Adam spends $14.40 on 3 stickers and 4 marbles.
A sticker costs $2.70 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 + 2.70
Total cost of 3 stickers and 4 marbles
= 3(1 u + 2.70) + 4 u
= 3 u + 8.10 + 4 u
= 3 u + 4 u + 8.10
= 7 u + 8.10
7 u + 8.10 = 14.40
7 u = 14.40 - 8.10
7 u = 6.30
1 u = 6.30 ÷ 7 = 0.90
Cost of 1 sticker
= 1 u + 2.70
= 0.90 + 2.70
= $3.60
(b)
Cost of 7 stickers
= 7 x 3.60
= $25.20
(c)
Cost of 1 marble and 7 stickers
= 0.90 + 25.20
= $26.10
(d)
Cost of 7 stickers more than 1 marble
= 25.20 - 0.90
= $24.30
Answer(s): (a) $3.60; (b) $25.20; (c) $26.10; (d) $24.30