Adam pays $19.60 for 1 marble and 7 stickers.
The marble costs $1.20 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 marbles and 3 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 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.20 + 7 u
= 8 u + 1.20
8 u + 1.20 = 19.60
8 u = 19.60 - 1.20
8 u = 18.40
1 u = 18.40 ÷ 8 = 2.30
Cost of 1 marble
= 2.30 + 1.20
= $3.50
(b)
Cost of 7 marbles and 3 stickers
= 7 x 3.50 + 3 x 2.30
= 24.50 + 6.90
= $31.40
Answer(s): (a) $3.50; (b) $31.40