Adam spends $16.80 on 3 stickers and 4 marbles.
A sticker costs $1.40 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 + 1.40
Total cost of 3 stickers and 4 marbles
= 3(1 u + 1.40) + 4 u
= 3 u + 4.20 + 4 u
= 3 u + 4 u + 4.20
= 7 u + 4.20
7 u + 4.20 = 16.80
7 u = 16.80 - 4.20
7 u = 12.60
1 u = 12.60 ÷ 7 = 1.80
Cost of 1 sticker
= 1 u + 1.40
= 1.80 + 1.40
= $3.20
(b)
Cost of 7 stickers
= 7 x 3.20
= $22.40
(c)
Cost of 1 marble and 7 stickers
= 1.80 + 22.40
= $24.20
(d)
Cost of 7 stickers more than 1 marble
= 22.40 - 1.80
= $20.60
Answer(s): (a) $3.20; (b) $22.40; (c) $24.20; (d) $20.60