Adam pays $12 for a marble and a sticker.
The sticker costs thrice as much as the marble.
- Find the cost of the marble.
- Find the cost of the sticker.
- Find the difference in the cost of the sticker and the marble.
(a)
Choose the cheaper item to be 1 u.
The sticker costs thrice as much as the marble.
The marble is cheaper.
Cost of the marble = 1 u
Cost of the sticker = 3 u
Total cost = 1 u + 3 u = 4 u
4 u = 12
1 u = 12 ÷ 4 = 3
Cost of the marble
= 1 u
= $3
(b)
Cost of the sticker
= 3 u
= 3 x 3
= $9
(c)
Difference in the cost of the sticker and the marble
= 3 u - 1 u
= 2 u
= 2 x 3
= $6
Answer(s): (a) $3; (b) $9; (c) $6