Adam pays $40.10 for 1 marble and 8 stickers.
The marble costs $1.40 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 + 1.40
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 1.40 + 8 u
= 9 u + 1.40
9 u + 1.40 = 40.10
9 u = 40.10 - 1.40
9 u = 38.70
1 u = 38.70 ÷ 9 = 4.30
Cost of 1 marble
= 4.30 + 1.40
= $5.70
(b)
Cost of 8 marbles and 7 stickers
= 8 x 5.70 + 7 x 4.30
= 45.60 + 30.10
= $75.70
Answer(s): (a) $5.70; (b) $75.70