Adam pays $18.90 for 1 marble and 4 stickers.
The marble costs $2.40 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 4 marbles and 7 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 2.40
Cost of 4 stickers
= 4 x 1 u
= 4 u
Total cost of 1 marble and 4 stickers
= 1 u + 2.40 + 4 u
= 5 u + 2.40
5 u + 2.40 = 18.90
5 u = 18.90 - 2.40
5 u = 16.50
1 u = 16.50 ÷ 5 = 3.30
Cost of 1 marble
= 3.30 + 2.40
= $5.70
(b)
Cost of 4 marbles and 7 stickers
= 4 x 5.70 + 7 x 3.30
= 22.80 + 23.10
= $45.90
Answer(s): (a) $5.70; (b) $45.90