Adam spends $16.60 on 4 marbles and 5 stickers.
A marble costs $2.80 more than 1 sticker.
- How much does 1 marble cost?
- How much do 8 marbles cost?
- How much do a sticker and 8 marbles cost?
- How much do 8 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 + 2.80
Total cost of 4 marbles and 5 stickers
= 4(1 u + 2.80) + 5 u
= 4 u + 11.20 + 5 u
= 4 u + 5 u + 11.20
= 9 u + 11.20
9 u + 11.20 = 16.60
9 u = 16.60 - 11.20
9 u = 5.40
1 u = 5.40 ÷ 9 = 0.60
Cost of 1 marble
= 1 u + 2.80
= 0.60 + 2.80
= $3.40
(b)
Cost of 8 marbles
= 8 x 3.40
= $27.20
(c)
Cost of 1 sticker and 8 marbles
= 0.60 + 27.20
= $27.80
(d)
Cost of 8 marbles more than 1 sticker
= 27.20 - 0.60
= $26.60
Answer(s): (a) $3.40; (b) $27.20; (c) $27.80; (d) $26.60