Adam pays $15.40 for 1 marble and 8 stickers.
The marble costs $1.90 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 + 1.90
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 1.90 + 8 u
= 9 u + 1.90
9 u + 1.90 = 15.40
9 u = 15.40 - 1.90
9 u = 13.50
1 u = 13.50 ÷ 9 = 1.50
Cost of 1 marble
= 1.50 + 1.90
= $3.40
(b)
Cost of 8 marbles and 7 stickers
= 8 x 3.40 + 7 x 1.50
= 27.20 + 10.50
= $37.70
Answer(s): (a) $3.40; (b) $37.70