Adam pays $15.30 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 8 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 = 15.30
8 u = 15.30 - 2.50
8 u = 12.80
1 u = 12.80 ÷ 8 = 1.60
Cost of 1 marble
= 1.60 + 2.50
= $4.10
(b)
Cost of 7 marbles and 8 stickers
= 7 x 4.10 + 8 x 1.60
= 28.70 + 12.80
= $41.50
Answer(s): (a) $4.10; (b) $41.50