Adam pays $36.30 for 1 marble and 7 stickers.
The marble costs $2.70 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 + 2.70
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 2.70 + 7 u
= 8 u + 2.70
8 u + 2.70 = 36.30
8 u = 36.30 - 2.70
8 u = 33.60
1 u = 33.60 ÷ 8 = 4.20
Cost of 1 marble
= 4.20 + 2.70
= $6.90
(b)
Cost of 7 marbles and 8 stickers
= 7 x 6.90 + 8 x 4.20
= 48.30 + 33.60
= $81.90
Answer(s): (a) $6.90; (b) $81.90