Adam pays $15.70 for 1 marble and 7 stickers.
The marble costs $2.10 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 marbles and 6 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 2.10
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 2.10 + 7 u
= 8 u + 2.10
8 u + 2.10 = 15.70
8 u = 15.70 - 2.10
8 u = 13.60
1 u = 13.60 ÷ 8 = 1.70
Cost of 1 marble
= 1.70 + 2.10
= $3.80
(b)
Cost of 7 marbles and 6 stickers
= 7 x 3.80 + 6 x 1.70
= 26.60 + 10.20
= $36.80
Answer(s): (a) $3.80; (b) $36.80