Adam pays $21.70 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 = 21.70
5 u = 21.70 - 1.20
5 u = 20.50
1 u = 20.50 ÷ 5 = 4.10
Cost of 1 marble
= 4.10 + 1.20
= $5.30
(b)
Cost of 4 marbles and 7 stickers
= 4 x 5.30 + 7 x 4.10
= 21.20 + 28.70
= $49.90
Answer(s): (a) $5.30; (b) $49.90