Adam pays $38.40 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 = 38.40
6 u = 38.40 - 1.20
6 u = 37.20
1 u = 37.20 ÷ 6 = 6.20
Cost of 1 marble
= 6.20 + 1.20
= $7.40
(b)
Cost of 5 marbles and 7 stickers
= 5 x 7.40 + 7 x 6.20
= 37.00 + 43.40
= $80.40
Answer(s): (a) $7.40; (b) $80.40