Adam pays $39.80 for 1 marble and 7 stickers.
The marble costs $1.40 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 7 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 + 1.40
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.40 + 7 u
= 8 u + 1.40
8 u + 1.40 = 39.80
8 u = 39.80 - 1.40
8 u = 38.40
1 u = 38.40 ÷ 8 = 4.80
Cost of 1 marble
= 4.80 + 1.40
= $6.20
(b)
Cost of 7 marbles and 8 stickers
= 7 x 6.20 + 8 x 4.80
= 43.40 + 38.40
= $81.80
Answer(s): (a) $6.20; (b) $81.80