Adam pays $40.90 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 = 40.90
9 u = 40.90 - 2.20
9 u = 38.70
1 u = 38.70 ÷ 9 = 4.30
Cost of 1 marble
= 4.30 + 2.20
= $6.50
(b)
Cost of 8 marbles and 7 stickers
= 8 x 6.50 + 7 x 4.30
= 52.00 + 30.10
= $82.10
Answer(s): (a) $6.50; (b) $82.10