Adam spends $14.10 on 5 marbles and 6 stickers.
A marble costs $1.50 more than 1 sticker.
- How much does 1 marble cost?
- How much do 7 marbles cost?
- How much do a sticker and 7 marbles cost?
- How much do 7 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 + 1.50
Total cost of 5 marbles and 6 stickers
= 5(1 u + 1.50) + 6 u
= 5 u + 7.50 + 6 u
= 5 u + 6 u + 7.50
= 11 u + 7.50
11 u + 7.50 = 14.10
11 u = 14.10 - 7.50
11 u = 6.60
1 u = 6.60 ÷ 11 = 0.60
Cost of 1 marble
= 1 u + 1.50
= 0.60 + 1.50
= $2.10
(b)
Cost of 7 marbles
= 7 x 2.10
= $14.70
(c)
Cost of 1 sticker and 7 marbles
= 0.60 + 14.70
= $15.30
(d)
Cost of 7 marbles more than 1 sticker
= 14.70 - 0.60
= $14.10
Answer(s): (a) $2.10; (b) $14.70; (c) $15.30; (d) $14.10