Adam pays $42.60 for 1 marble and 7 stickers.
The marble costs $1.80 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 marbles and 2 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 1.80
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.80 + 7 u
= 8 u + 1.80
8 u + 1.80 = 42.60
8 u = 42.60 - 1.80
8 u = 40.80
1 u = 40.80 ÷ 8 = 5.10
Cost of 1 marble
= 5.10 + 1.80
= $6.90
(b)
Cost of 7 marbles and 2 stickers
= 7 x 6.90 + 2 x 5.10
= 48.30 + 10.20
= $58.50
Answer(s): (a) $6.90; (b) $58.50