Adam pays $38.90 for 1 marble and 5 stickers.
The marble costs $1.10 more than each sticker.
- What is the cost of 1 marble?
- How much is the cost of 5 marbles and 7 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 5 stickers
= 5 x 1 u
= 5 u
Total cost of 1 marble and 5 stickers
= 1 u + 1.10 + 5 u
= 6 u + 1.10
6 u + 1.10 = 38.90
6 u = 38.90 - 1.10
6 u = 37.80
1 u = 37.80 ÷ 6 = 6.30
Cost of 1 marble
= 6.30 + 1.10
= $7.40
(b)
Cost of 5 marbles and 7 stickers
= 5 x 7.40 + 7 x 6.30
= 37.00 + 44.10
= $81.10
Answer(s): (a) $7.40; (b) $81.10