Adam pays $37.50 for 1 marble and 8 stickers.
The marble costs $2.40 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 8 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 + 2.40
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 2.40 + 8 u
= 9 u + 2.40
9 u + 2.40 = 37.50
9 u = 37.50 - 2.40
9 u = 35.10
1 u = 35.10 ÷ 9 = 3.90
Cost of 1 marble
= 3.90 + 2.40
= $6.30
(b)
Cost of 8 marbles and 7 stickers
= 8 x 6.30 + 7 x 3.90
= 50.40 + 27.30
= $77.70
Answer(s): (a) $6.30; (b) $77.70