Adam spends $16.10 on 3 marbles and 4 stickers.
A marble costs $1.40 more than 1 sticker.
- How much does 1 marble cost?
- How much do 8 marbles cost?
- How much do a sticker and 8 marbles cost?
- How much do 8 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 + 1.40
Total cost of 3 marbles and 4 stickers
= 3(1 u + 1.40) + 4 u
= 3 u + 4.20 + 4 u
= 3 u + 4 u + 4.20
= 7 u + 4.20
7 u + 4.20 = 16.10
7 u = 16.10 - 4.20
7 u = 11.90
1 u = 11.90 ÷ 7 = 1.70
Cost of 1 marble
= 1 u + 1.40
= 1.70 + 1.40
= $3.10
(b)
Cost of 8 marbles
= 8 x 3.10
= $24.80
(c)
Cost of 1 sticker and 8 marbles
= 1.70 + 24.80
= $26.50
(d)
Cost of 8 marbles more than 1 sticker
= 24.80 - 1.70
= $23.10
Answer(s): (a) $3.10; (b) $24.80; (c) $26.50; (d) $23.10