Adam pays $25.90 for 1 marble and 7 stickers.
The marble costs $1.10 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 + 1.10
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.10 + 7 u
= 8 u + 1.10
8 u + 1.10 = 25.90
8 u = 25.90 - 1.10
8 u = 24.80
1 u = 24.80 ÷ 8 = 3.10
Cost of 1 marble
= 3.10 + 1.10
= $4.20
(b)
Cost of 7 marbles and 3 stickers
= 7 x 4.20 + 3 x 3.10
= 29.40 + 9.30
= $38.70
Answer(s): (a) $4.20; (b) $38.70