Adam pays $39.90 for 1 marble and 4 stickers.
The marble costs $1.40 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 4 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 4 stickers
= 4 x 1 u
= 4 u
Total cost of 1 marble and 4 stickers
= 1 u + 1.40 + 4 u
= 5 u + 1.40
5 u + 1.40 = 39.90
5 u = 39.90 - 1.40
5 u = 38.50
1 u = 38.50 ÷ 5 = 7.70
Cost of 1 marble
= 7.70 + 1.40
= $9.10
(b)
Cost of 4 marbles and 7 stickers
= 4 x 9.10 + 7 x 7.70
= 36.40 + 53.90
= $90.30
Answer(s): (a) $9.10; (b) $90.30