Adam pays $18.90 for 1 marble and 7 stickers.
The marble costs $1.30 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 marbles and 4 stickers?
(a)
Choose the cheaper item to be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 1 u + 1.30
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.30 + 7 u
= 8 u + 1.30
8 u + 1.30 = 18.90
8 u = 18.90 - 1.30
8 u = 17.60
1 u = 17.60 ÷ 8 = 2.20
Cost of 1 marble
= 2.20 + 1.30
= $3.50
(b)
Cost of 7 marbles and 4 stickers
= 7 x 3.50 + 4 x 2.20
= 24.50 + 8.80
= $33.30
Answer(s): (a) $3.50; (b) $33.30