Adam spends $12.30 on 2 marbles and 3 stickers.
A marble costs $1.90 more than 1 sticker.
- How much does 1 marble cost?
- How much do 3 marbles cost?
- How much do a sticker and 3 marbles cost?
- How much do 3 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 + 1.90
Total cost of 2 marbles and 3 stickers
= 2(1 u + 1.90) + 3 u
= 2 u + 3.80 + 3 u
= 2 u + 3 u + 3.80
= 5 u + 3.80
5 u + 3.80 = 12.30
5 u = 12.30 - 3.80
5 u = 8.50
1 u = 8.50 ÷ 5 = 1.70
Cost of 1 marble
= 1 u + 1.90
= 1.70 + 1.90
= $3.60
(b)
Cost of 3 marbles
= 3 x 3.60
= $10.80
(c)
Cost of 1 sticker and 3 marbles
= 1.70 + 10.80
= $12.50
(d)
Cost of 3 marbles more than 1 sticker
= 10.80 - 1.70
= $9.10
Answer(s): (a) $3.60; (b) $10.80; (c) $12.50; (d) $9.10