Adam spends $15.20 on 3 stickers and 4 marbles.
A sticker costs $1.80 more than 1 marble.
- How much does 1 sticker cost?
- How much do 6 stickers cost?
- How much do a marble and 6 stickers cost?
- How much do 6 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 + 1.80
Total cost of 3 stickers and 4 marbles
= 3(1 u + 1.80) + 4 u
= 3 u + 5.40 + 4 u
= 3 u + 4 u + 5.40
= 7 u + 5.40
7 u + 5.40 = 15.20
7 u = 15.20 - 5.40
7 u = 9.80
1 u = 9.80 ÷ 7 = 1.40
Cost of 1 sticker
= 1 u + 1.80
= 1.40 + 1.80
= $3.20
(b)
Cost of 6 stickers
= 6 x 3.20
= $19.20
(c)
Cost of 1 marble and 6 stickers
= 1.40 + 19.20
= $20.60
(d)
Cost of 6 stickers more than 1 marble
= 19.20 - 1.40
= $17.80
Answer(s): (a) $3.20; (b) $19.20; (c) $20.60; (d) $17.80