Adam pays $16.20 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 4 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 = 16.20
8 u = 16.20 - 1.80
8 u = 14.40
1 u = 14.40 ÷ 8 = 1.80
Cost of 1 marble
= 1.80 + 1.80
= $3.60
(b)
Cost of 7 marbles and 4 stickers
= 7 x 3.60 + 4 x 1.80
= 25.20 + 7.20
= $32.40
Answer(s): (a) $3.60; (b) $32.40