Adam pays $21.50 for 1 marble and 7 stickers.
The marble costs $2.30 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 marbles and 3 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 2.30
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 2.30 + 7 u
= 8 u + 2.30
8 u + 2.30 = 21.50
8 u = 21.50 - 2.30
8 u = 19.20
1 u = 19.20 ÷ 8 = 2.40
Cost of 1 marble
= 2.40 + 2.30
= $4.70
(b)
Cost of 7 marbles and 3 stickers
= 7 x 4.70 + 3 x 2.40
= 32.90 + 7.20
= $40.10
Answer(s): (a) $4.70; (b) $40.10