Adam pays $19.50 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 7 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 = 19.50
7 u = 19.50 - 1.30
7 u = 18.20
1 u = 18.20 ÷ 7 = 2.60
Cost of 1 marble
= 2.60 + 1.30
= $3.90
(b)
Cost of 6 marbles and 7 stickers
= 6 x 3.90 + 7 x 2.60
= 23.40 + 18.20
= $41.60
Answer(s): (a) $3.90; (b) $41.60