Adam pays $42.30 for 1 marble and 8 stickers.
The marble costs $1.80 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 8 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 + 1.80
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 1.80 + 8 u
= 9 u + 1.80
9 u + 1.80 = 42.30
9 u = 42.30 - 1.80
9 u = 40.50
1 u = 40.50 ÷ 9 = 4.50
Cost of 1 marble
= 4.50 + 1.80
= $6.30
(b)
Cost of 8 marbles and 5 stickers
= 8 x 6.30 + 5 x 4.50
= 50.40 + 22.50
= $72.90
Answer(s): (a) $6.30; (b) $72.90