Adam buys a marble for $9.
He also buys a bead.
The marble costs 3 times as much as the bead.
- How much less does the bead cost than the marble?
- How much does he spend altogether?
- How much are 5 beads?
- What is the difference in cost between 2 marbles and 2 beads?
(a)
Choose the cheaper item to be 1 u.
The marble costs 3 times as much as the bead.
The bead is cheaper.
Cost of the bead = 1 u
Cost of the marble = 3 u = $9
3 u = 9
1 u = 9 ÷ 3 = 3
Amount that the bead 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 5 beads
= 5 x 1 u
= 5 u
= 5 x 3
= $15
(d )
Difference in the cost between 6 marbles and 2 beads
= (2 x 3 u) - (2 x 1 u)
= 6 u - 2 u
= 4 u
= 4 x 3
= $12
Answer(s): (a) $6; (b) $12; (c) $15; (d) $12