Adam buys a marble for $9.
He also buys a sticker.
The marble costs 3 times as much as the sticker.
- How much less does the sticker cost than the marble?
- How much does he spend altogether?
- How much are 7 stickers?
- What is the difference in cost between 4 marbles and 4 stickers?
(a)
Choose the cheaper item to be 1 u.
The marble costs 3 times as much as the sticker.
The sticker is cheaper.
Cost of the sticker = 1 u
Cost of the marble = 3 u = $9
3 u = 9
1 u = 9 ÷ 3 = 3
Amount that the sticker costs less than the marble
= 3 u - 1 u
= 2 u
= 2 x 3
= $6
(b)
Total amount that Adam spends
= 1 u + 3 u
= 4 u
= 4 x 3
= $12
(c)
Cost of 7 stickers
= 7 x 1 u
= 7 u
= 7 x 3
= $21
(d )
Difference in the cost between 6 marbles and 4 stickers
= (4 x 3 u) - (4 x 1 u)
= 12 u - 4 u
= 8 u
= 8 x 3
= $24
Answer(s): (a) $6; (b) $12; (c) $21; (d) $24