Adam pays $37.90 for 1 marble and 7 stickers.
The marble costs $1.10 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 + 1.10
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.10 + 7 u
= 8 u + 1.10
8 u + 1.10 = 37.90
8 u = 37.90 - 1.10
8 u = 36.80
1 u = 36.80 ÷ 8 = 4.60
Cost of 1 marble
= 4.60 + 1.10
= $5.70
(b)
Cost of 7 marbles and 8 stickers
= 7 x 5.70 + 8 x 4.60
= 39.90 + 36.80
= $76.70
Answer(s): (a) $5.70; (b) $76.70