Adam pays $17.40 for 1 marble and 8 stickers.
The marble costs $2.10 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 + 2.10
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 2.10 + 8 u
= 9 u + 2.10
9 u + 2.10 = 17.40
9 u = 17.40 - 2.10
9 u = 15.30
1 u = 15.30 ÷ 9 = 1.70
Cost of 1 marble
= 1.70 + 2.10
= $3.80
(b)
Cost of 8 marbles and 4 stickers
= 8 x 3.80 + 4 x 1.70
= 30.40 + 6.80
= $37.20
Answer(s): (a) $3.80; (b) $37.20