Adam pays $38.90 for 1 marble and 6 stickers.
The marble costs $2.50 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 6 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 + 2.50
Cost of 6 stickers
= 6 x 1 u
= 6 u
Total cost of 1 marble and 6 stickers
= 1 u + 2.50 + 6 u
= 7 u + 2.50
7 u + 2.50 = 38.90
7 u = 38.90 - 2.50
7 u = 36.40
1 u = 36.40 ÷ 7 = 5.20
Cost of 1 marble
= 5.20 + 2.50
= $7.70
(b)
Cost of 6 marbles and 3 stickers
= 6 x 7.70 + 3 x 5.20
= 46.20 + 15.60
= $61.80
Answer(s): (a) $7.70; (b) $61.80