Adam pays $39.80 for 1 marble and 6 stickers.
The marble costs $1.30 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 6 marbles and 8 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 6 stickers
= 6 x 1 u
= 6 u
Total cost of 1 marble and 6 stickers
= 1 u + 1.30 + 6 u
= 7 u + 1.30
7 u + 1.30 = 39.80
7 u = 39.80 - 1.30
7 u = 38.50
1 u = 38.50 ÷ 7 = 5.50
Cost of 1 marble
= 5.50 + 1.30
= $6.80
(b)
Cost of 6 marbles and 8 stickers
= 6 x 6.80 + 8 x 5.50
= 40.80 + 44.00
= $84.80
Answer(s): (a) $6.80; (b) $84.80