Adam pays $18.20 for 1 marble and 8 stickers.
The marble costs $2.90 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 + 2.90
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 2.90 + 8 u
= 9 u + 2.90
9 u + 2.90 = 18.20
9 u = 18.20 - 2.90
9 u = 15.30
1 u = 15.30 ÷ 9 = 1.70
Cost of 1 marble
= 1.70 + 2.90
= $4.60
(b)
Cost of 8 marbles and 7 stickers
= 8 x 4.60 + 7 x 1.70
= 36.80 + 11.90
= $48.70
Answer(s): (a) $4.60; (b) $48.70