Adam spends $16.80 on 2 marbles and 3 beads.
A marble costs 2 times as much as 1 bead.
- How much does 1 marble cost?
- How much do 4 marbles cost?
- How much do a bead and 4 marbles cost?
- How much does 1 bead cost less than 4 marbles?
(a)
Let the cheaper item be 1 u.
Cost of 1 bead = 1 u
Cost of 1 marble = 2 u
Cost of 2 marbles = 2 x 2 u = 4 u
Cost of 3 beads = 3 x 1 u = 3 u
Total cost of 2 marbles and 3 beads
= 4 u + 3 u
= 7 u
7 u = 16.80
1 u = 16.80 ÷ 7 = 2.40
Cost of 1 marble
= 2 u
= 2 x 2.40
= $4.80
(b)
Cost of 4 marbles
= 4 x 4.80
= $19.20
(c)
Cost of 1 bead and 4 marbles
= 2.40 + 19.20
= $21.60
(d)
Cost of 1 bead less than 4 marbles
= 19.20 - 2.40
= $16.80
Answer(s): (a) $4.80; (b) $19.20; (c) $21.60; (d) $16.80