Adam pays $21.90 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 5 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 = 21.90
8 u = 21.90 - 1.10
8 u = 20.80
1 u = 20.80 ÷ 8 = 2.60
Cost of 1 marble
= 2.60 + 1.10
= $3.70
(b)
Cost of 7 marbles and 5 stickers
= 7 x 3.70 + 5 x 2.60
= 25.90 + 13.00
= $38.90
Answer(s): (a) $3.70; (b) $38.90