Adam pays $30.90 for 1 marble and 6 stickers.
The marble costs $1.50 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 6 marbles and 8 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 1.50
Cost of 6 stickers
= 6 x 1 u
= 6 u
Total cost of 1 marble and 6 stickers
= 1 u + 1.50 + 6 u
= 7 u + 1.50
7 u + 1.50 = 30.90
7 u = 30.90 - 1.50
7 u = 29.40
1 u = 29.40 ÷ 7 = 4.20
Cost of 1 marble
= 4.20 + 1.50
= $5.70
(b)
Cost of 6 marbles and 8 stickers
= 6 x 5.70 + 8 x 4.20
= 34.20 + 33.60
= $67.80
Answer(s): (a) $5.70; (b) $67.80