Adam spends $15.90 on 2 marbles and 3 stickers.
A marble costs $1.20 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 + 1.20
Total cost of 2 marbles and 3 stickers
= 2(1 u + 1.20) + 3 u
= 2 u + 2.40 + 3 u
= 2 u + 3 u + 2.40
= 5 u + 2.40
5 u + 2.40 = 15.90
5 u = 15.90 - 2.40
5 u = 13.50
1 u = 13.50 ÷ 5 = 2.70
Cost of 1 marble
= 1 u + 1.20
= 2.70 + 1.20
= $3.90
(b)
Cost of 6 marbles
= 6 x 3.90
= $23.40
(c)
Cost of 1 sticker and 6 marbles
= 2.70 + 23.40
= $26.10
(d)
Cost of 6 marbles more than 1 sticker
= 23.40 - 2.70
= $20.70
Answer(s): (a) $3.90; (b) $23.40; (c) $26.10; (d) $20.70