Adam pays $36.90 for 1 marble and 7 stickers.
The marble costs $1.70 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 marbles and 8 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 1.70
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.70 + 7 u
= 8 u + 1.70
8 u + 1.70 = 36.90
8 u = 36.90 - 1.70
8 u = 35.20
1 u = 35.20 ÷ 8 = 4.40
Cost of 1 marble
= 4.40 + 1.70
= $6.10
(b)
Cost of 7 marbles and 8 stickers
= 7 x 6.10 + 8 x 4.40
= 42.70 + 35.20
= $77.90
Answer(s): (a) $6.10; (b) $77.90