Adam spends $13.80 on 3 stickers and 4 marbles.
A sticker costs $1.10 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 + 1.10
Total cost of 3 stickers and 4 marbles
= 3(1 u + 1.10) + 4 u
= 3 u + 3.30 + 4 u
= 3 u + 4 u + 3.30
= 7 u + 3.30
7 u + 3.30 = 13.80
7 u = 13.80 - 3.30
7 u = 10.50
1 u = 10.50 ÷ 7 = 1.50
Cost of 1 sticker
= 1 u + 1.10
= 1.50 + 1.10
= $2.60
(b)
Cost of 4 stickers
= 4 x 2.60
= $10.40
(c)
Cost of 1 marble and 4 stickers
= 1.50 + 10.40
= $11.90
(d)
Cost of 4 stickers more than 1 marble
= 10.40 - 1.50
= $8.90
Answer(s): (a) $2.60; (b) $10.40; (c) $11.90; (d) $8.90