Adam spends $13.40 on 3 marbles and 4 stickers.
A marble costs $2.60 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 + 2.60
Total cost of 3 marbles and 4 stickers
= 3(1 u + 2.60) + 4 u
= 3 u + 7.80 + 4 u
= 3 u + 4 u + 7.80
= 7 u + 7.80
7 u + 7.80 = 13.40
7 u = 13.40 - 7.80
7 u = 5.60
1 u = 5.60 ÷ 7 = 0.80
Cost of 1 marble
= 1 u + 2.60
= 0.80 + 2.60
= $3.40
(b)
Cost of 6 marbles
= 6 x 3.40
= $20.40
(c)
Cost of 1 sticker and 6 marbles
= 0.80 + 20.40
= $21.20
(d)
Cost of 6 marbles more than 1 sticker
= 20.40 - 0.80
= $19.60
Answer(s): (a) $3.40; (b) $20.40; (c) $21.20; (d) $19.60
