Adam spends $16.40 on 4 marbles and 5 stickers.
A marble costs $2.30 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 + 2.30
Total cost of 4 marbles and 5 stickers
= 4(1 u + 2.30) + 5 u
= 4 u + 9.20 + 5 u
= 4 u + 5 u + 9.20
= 9 u + 9.20
9 u + 9.20 = 16.40
9 u = 16.40 - 9.20
9 u = 7.20
1 u = 7.20 ÷ 9 = 0.80
Cost of 1 marble
= 1 u + 2.30
= 0.80 + 2.30
= $3.10
(b)
Cost of 6 marbles
= 6 x 3.10
= $18.60
(c)
Cost of 1 sticker and 6 marbles
= 0.80 + 18.60
= $19.40
(d)
Cost of 6 marbles more than 1 sticker
= 18.60 - 0.80
= $17.80
Answer(s): (a) $3.10; (b) $18.60; (c) $19.40; (d) $17.80