Adam spends $15.80 on 3 stickers and 4 marbles.
A sticker costs $2.70 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 + 2.70
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 = 15.80
7 u = 15.80 - 8.10
7 u = 7.70
1 u = 7.70 ÷ 7 = 1.10
Cost of 1 sticker
= 1 u + 2.70
= 1.10 + 2.70
= $3.80
(b)
Cost of 4 stickers
= 4 x 3.80
= $15.20
(c)
Cost of 1 marble and 4 stickers
= 1.10 + 15.20
= $16.30
(d)
Cost of 4 stickers more than 1 marble
= 15.20 - 1.10
= $14.10
Answer(s): (a) $3.80; (b) $15.20; (c) $16.30; (d) $14.10