Adam pays $20.20 for 1 marble and 8 stickers.
The marble costs $1.30 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 8 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 + 1.30
Cost of 8 stickers
= 8 x 1 u
= 8 u
Total cost of 1 marble and 8 stickers
= 1 u + 1.30 + 8 u
= 9 u + 1.30
9 u + 1.30 = 20.20
9 u = 20.20 - 1.30
9 u = 18.90
1 u = 18.90 ÷ 9 = 2.10
Cost of 1 marble
= 2.10 + 1.30
= $3.40
(b)
Cost of 8 marbles and 7 stickers
= 8 x 3.40 + 7 x 2.10
= 27.20 + 14.70
= $41.90
Answer(s): (a) $3.40; (b) $41.90