Adam pays $21.70 for 1 marble and 6 stickers.
The marble costs $2.80 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 6 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 + 2.80
Cost of 6 stickers
= 6 x 1 u
= 6 u
Total cost of 1 marble and 6 stickers
= 1 u + 2.80 + 6 u
= 7 u + 2.80
7 u + 2.80 = 21.70
7 u = 21.70 - 2.80
7 u = 18.90
1 u = 18.90 ÷ 7 = 2.70
Cost of 1 marble
= 2.70 + 2.80
= $5.50
(b)
Cost of 6 marbles and 7 stickers
= 6 x 5.50 + 7 x 2.70
= 33.00 + 18.90
= $51.90
Answer(s): (a) $5.50; (b) $51.90