Adam pays $23.80 for 1 marble and 8 stickers.
The marble costs $2.20 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 8 marbles and 7 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 2.20
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 2.20 + 8 u
= 9 u + 2.20
9 u + 2.20 = 23.80
9 u = 23.80 - 2.20
9 u = 21.60
1 u = 21.60 ÷ 9 = 2.40
Cost of 1 marble
= 2.40 + 2.20
= $4.60
(b)
Cost of 8 marbles and 7 stickers
= 8 x 4.60 + 7 x 2.40
= 36.80 + 16.80
= $53.60
Answer(s): (a) $4.60; (b) $53.60