Adam pays $15.10 for 1 marble and 8 stickers.
The marble costs $2.50 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 8 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 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 2.50 + 8 u
= 9 u + 2.50
9 u + 2.50 = 15.10
9 u = 15.10 - 2.50
9 u = 12.60
1 u = 12.60 ÷ 9 = 1.40
Cost of 1 marble
= 1.40 + 2.50
= $3.90
(b)
Cost of 8 marbles and 3 stickers
= 8 x 3.90 + 3 x 1.40
= 31.20 + 4.20
= $35.40
Answer(s): (a) $3.90; (b) $35.40