Adam pays $16.80 for 1 marble and 7 stickers.
The marble costs $1.60 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 + 1.60
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.60 + 7 u
= 8 u + 1.60
8 u + 1.60 = 16.80
8 u = 16.80 - 1.60
8 u = 15.20
1 u = 15.20 ÷ 8 = 1.90
Cost of 1 marble
= 1.90 + 1.60
= $3.50
(b)
Cost of 7 marbles and 8 stickers
= 7 x 3.50 + 8 x 1.90
= 24.50 + 15.20
= $39.70
Answer(s): (a) $3.50; (b) $39.70