Adam pays $38.70 for 1 marble and 4 stickers.
The marble costs $1.20 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 + 1.20
Cost of 4 stickers
= 4 x 1 u
= 4 u
Total cost of 1 marble and 4 stickers
= 1 u + 1.20 + 4 u
= 5 u + 1.20
5 u + 1.20 = 38.70
5 u = 38.70 - 1.20
5 u = 37.50
1 u = 37.50 ÷ 5 = 7.50
Cost of 1 marble
= 7.50 + 1.20
= $8.70
(b)
Cost of 4 marbles and 7 stickers
= 4 x 8.70 + 7 x 7.50
= 34.80 + 52.50
= $87.30
Answer(s): (a) $8.70; (b) $87.30