Adam pays $39.70 for 1 marble and 4 stickers.
The marble costs $1.20 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 4 marbles and 8 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 1.20
Cost of 4 stickers
= 4 x 1 u
= 4 u
Total cost of 1 marble and 4 stickers
= 1 u + 1.20 + 4 u
= 5 u + 1.20
5 u + 1.20 = 39.70
5 u = 39.70 - 1.20
5 u = 38.50
1 u = 38.50 ÷ 5 = 7.70
Cost of 1 marble
= 7.70 + 1.20
= $8.90
(b)
Cost of 4 marbles and 8 stickers
= 4 x 8.90 + 8 x 7.70
= 35.60 + 61.60
= $97.20
Answer(s): (a) $8.90; (b) $97.20