Adam pays $18.60 for 1 marble and 7 stickers.
The marble costs $1.80 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 + 1.80
Cost of 7 stickers
= 7 x 1 u
= 7 u
Total cost of 1 marble and 7 stickers
= 1 u + 1.80 + 7 u
= 8 u + 1.80
8 u + 1.80 = 18.60
8 u = 18.60 - 1.80
8 u = 16.80
1 u = 16.80 ÷ 8 = 2.10
Cost of 1 marble
= 2.10 + 1.80
= $3.90
(b)
Cost of 7 marbles and 3 stickers
= 7 x 3.90 + 3 x 2.10
= 27.30 + 6.30
= $33.60
Answer(s): (a) $3.90; (b) $33.60