Adam pays $23.40 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 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 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 = 23.40
9 u = 23.40 - 1.80
9 u = 21.60
1 u = 21.60 ÷ 9 = 2.40
Cost of 1 marble
= 2.40 + 1.80
= $4.20
(b)
Cost of 8 marbles and 2 stickers
= 8 x 4.20 + 2 x 2.40
= 33.60 + 4.80
= $38.40
Answer(s): (a) $4.20; (b) $38.40