Adam pays $15.80 for 1 marble and 6 stickers.
The marble costs $1.10 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 6 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 6 stickers
= 6 x 1 u
= 6 u
Total cost of 1 marble and 6 stickers
= 1 u + 1.10 + 6 u
= 7 u + 1.10
7 u + 1.10 = 15.80
7 u = 15.80 - 1.10
7 u = 14.70
1 u = 14.70 ÷ 7 = 2.10
Cost of 1 marble
= 2.10 + 1.10
= $3.20
(b)
Cost of 6 marbles and 3 stickers
= 6 x 3.20 + 3 x 2.10
= 19.20 + 6.30
= $25.50
Answer(s): (a) $3.20; (b) $25.50