Adam pays $39.90 for 1 marble and 7 stickers.
The marble costs $1.50 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 + 1.50
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.50 + 7 u
= 8 u + 1.50
8 u + 1.50 = 39.90
8 u = 39.90 - 1.50
8 u = 38.40
1 u = 38.40 ÷ 8 = 4.80
Cost of 1 marble
= 4.80 + 1.50
= $6.30
(b)
Cost of 7 marbles and 3 stickers
= 7 x 6.30 + 3 x 4.80
= 44.10 + 14.40
= $58.50
Answer(s): (a) $6.30; (b) $58.50