Adam spends $12.30 on 3 marbles and 4 beads.
A marble costs $2.70 more than 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 do 4 marbles cost more than 1 bead?
(a)
Let the cheaper item be 1 u.
Cost of 1 bead = 1 u
Cost of 1 marble = 1 u + 2.70
Total cost of 3 marbles and 4 beads
= 3(1 u + 2.70) + 4 u
= 3 u + 8.10 + 4 u
= 3 u + 4 u + 8.10
= 7 u + 8.10
7 u + 8.10 = 12.30
7 u = 12.30 - 8.10
7 u = 4.20
1 u = 4.20 ÷ 7 = 0.60
Cost of 1 marble
= 1 u + 2.70
= 0.60 + 2.70
= $3.30
(b)
Cost of 4 marbles
= 4 x 3.30
= $13.20
(c)
Cost of 1 bead and 4 marbles
= 0.60 + 13.20
= $13.80
(d)
Cost of 4 marbles more than 1 bead
= 13.20 - 0.60
= $12.60
Answer(s): (a) $3.30; (b) $13.20; (c) $13.80; (d) $12.60