Adam spends $13.60 on 4 marbles and 5 stickers.
A marble costs $1.60 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 + 1.60
Total cost of 4 marbles and 5 stickers
= 4(1 u + 1.60) + 5 u
= 4 u + 6.40 + 5 u
= 4 u + 5 u + 6.40
= 9 u + 6.40
9 u + 6.40 = 13.60
9 u = 13.60 - 6.40
9 u = 7.20
1 u = 7.20 ÷ 9 = 0.80
Cost of 1 marble
= 1 u + 1.60
= 0.80 + 1.60
= $2.40
(b)
Cost of 6 marbles
= 6 x 2.40
= $14.40
(c)
Cost of 1 sticker and 6 marbles
= 0.80 + 14.40
= $15.20
(d)
Cost of 6 marbles more than 1 sticker
= 14.40 - 0.80
= $13.60
Answer(s): (a) $2.40; (b) $14.40; (c) $15.20; (d) $13.60