Adam pays $31.90 for 1 marble and 8 stickers.
The marble costs $1.30 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 8 marbles and 4 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 1.30
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 1.30 + 8 u
= 9 u + 1.30
9 u + 1.30 = 31.90
9 u = 31.90 - 1.30
9 u = 30.60
1 u = 30.60 ÷ 9 = 3.40
Cost of 1 marble
= 3.40 + 1.30
= $4.70
(b)
Cost of 8 marbles and 4 stickers
= 8 x 4.70 + 4 x 3.40
= 37.60 + 13.60
= $51.20
Answer(s): (a) $4.70; (b) $51.20