Adam pays $39.70 for 1 marble and 7 stickers.
The marble costs $2.90 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 + 2.90
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 2.90 + 7 u
= 8 u + 2.90
8 u + 2.90 = 39.70
8 u = 39.70 - 2.90
8 u = 36.80
1 u = 36.80 ÷ 8 = 4.60
Cost of 1 marble
= 4.60 + 2.90
= $7.50
(b)
Cost of 7 marbles and 6 stickers
= 7 x 7.50 + 6 x 4.60
= 52.50 + 27.60
= $80.10
Answer(s): (a) $7.50; (b) $80.10