Adam spends $13.20 on 4 marbles and 5 stickers.
A marble costs $2.40 more than 1 sticker.
- How much does 1 marble cost?
- How much do 6 marbles cost?
- How much do a sticker and 6 marbles cost?
- How much do 6 marbles cost more than 1 sticker?
(a)
Let the cheaper item be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 2.40
Total cost of 4 marbles and 5 stickers
= 4(1 u + 2.40) + 5 u
= 4 u + 9.60 + 5 u
= 4 u + 5 u + 9.60
= 9 u + 9.60
9 u + 9.60 = 13.20
9 u = 13.20 - 9.60
9 u = 3.60
1 u = 3.60 ÷ 9 = 0.40
Cost of 1 marble
= 1 u + 2.40
= 0.40 + 2.40
= $2.80
(b)
Cost of 6 marbles
= 6 x 2.80
= $16.80
(c)
Cost of 1 sticker and 6 marbles
= 0.40 + 16.80
= $17.20
(d)
Cost of 6 marbles more than 1 sticker
= 16.80 - 0.40
= $16.40
Answer(s): (a) $2.80; (b) $16.80; (c) $17.20; (d) $16.40