Adam pays $26.90 for 1 marble and 7 stickers.
The marble costs $2.10 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 + 2.10
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 2.10 + 7 u
= 8 u + 2.10
8 u + 2.10 = 26.90
8 u = 26.90 - 2.10
8 u = 24.80
1 u = 24.80 ÷ 8 = 3.10
Cost of 1 marble
= 3.10 + 2.10
= $5.20
(b)
Cost of 7 marbles and 3 stickers
= 7 x 5.20 + 3 x 3.10
= 36.40 + 9.30
= $45.70
Answer(s): (a) $5.20; (b) $45.70