Adam spends $15.70 on 2 stickers and 3 marbles.
A sticker costs $2.10 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 + 2.10
Total cost of 2 stickers and 3 marbles
= 2(1 u + 2.10) + 3 u
= 2 u + 4.20 + 3 u
= 2 u + 3 u + 4.20
= 5 u + 4.20
5 u + 4.20 = 15.70
5 u = 15.70 - 4.20
5 u = 11.50
1 u = 11.50 ÷ 5 = 2.30
Cost of 1 sticker
= 1 u + 2.10
= 2.30 + 2.10
= $4.40
(b)
Cost of 4 stickers
= 4 x 4.40
= $17.60
(c)
Cost of 1 marble and 4 stickers
= 2.30 + 17.60
= $19.90
(d)
Cost of 4 stickers more than 1 marble
= 17.60 - 2.30
= $15.30
Answer(s): (a) $4.40; (b) $17.60; (c) $19.90; (d) $15.30