Adam pays $33.70 for 1 marble and 7 stickers.
The marble costs $2.50 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 + 2.50
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 2.50 + 7 u
= 8 u + 2.50
8 u + 2.50 = 33.70
8 u = 33.70 - 2.50
8 u = 31.20
1 u = 31.20 ÷ 8 = 3.90
Cost of 1 marble
= 3.90 + 2.50
= $6.40
(b)
Cost of 7 marbles and 3 stickers
= 7 x 6.40 + 3 x 3.90
= 44.80 + 11.70
= $56.50
Answer(s): (a) $6.40; (b) $56.50