Adam pays $22.10 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 = 22.10
8 u = 22.10 - 1.30
8 u = 20.80
1 u = 20.80 ÷ 8 = 2.60
Cost of 1 marble
= 2.60 + 1.30
= $3.90
(b)
Cost of 7 marbles and 4 stickers
= 7 x 3.90 + 4 x 2.60
= 27.30 + 10.40
= $37.70
Answer(s): (a) $3.90; (b) $37.70