Adam buys a marble for $9.
He also buys a bead.
The bead costs 3 times as much as the marble.
- How much less does the bead cost than the marble?
- How much does he spend altogether?
- How much are 2 beads?
- How much are 2 beads and 4 marbles?
(a)
Choose the cheaper item to be 1 u.
The bead costs 3 times as much as the marble.
The marble is cheaper.
Cost of the marble = 1 u = $9
Cost of the bead = 3 u
Amount that the marble costs less than the bead
= 3 u - 1 u
= 2 u
= 2 x 9
= $18
(b)
Total amount that Adam spends
= 1 u + 3 u
= 4 u
= 4 x 9
= $36
(c)
Cost of 2 beads
= 2 x 3 u
= 6 u
= 6 x 9
= $54
(d )
Cost of 2 beads and 4 marbles
= 2 x 3 u + 4 x 1 u
= 6 u + 4 u
= 10 u
= 10 x 9
= $90
Answer(s): (a) $18; (b) $36; (c) $54; (d) $90