Adam pays $15.60 for 1 marble and 5 stickers.
The marble costs $1.20 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 5 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 + 1.20
Cost of 5 stickers
= 5 x 1 u
= 5 u
Total cost of 1 marble and 5 stickers
= 1 u + 1.20 + 5 u
= 6 u + 1.20
6 u + 1.20 = 15.60
6 u = 15.60 - 1.20
6 u = 14.40
1 u = 14.40 ÷ 6 = 2.40
Cost of 1 marble
= 2.40 + 1.20
= $3.60
(b)
Cost of 5 marbles and 7 stickers
= 5 x 3.60 + 7 x 2.40
= 18.00 + 16.80
= $34.80
Answer(s): (a) $3.60; (b) $34.80