Adam spends $12.20 on 4 marbles and 5 beads.
A marble costs $1.70 more than 1 bead.
- How much does 1 marble cost?
- How much do 6 marbles cost?
- How much do a bead and 6 marbles cost?
- How much do 6 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 + 1.70
Total cost of 4 marbles and 5 beads
= 4(1 u + 1.70) + 5 u
= 4 u + 6.80 + 5 u
= 4 u + 5 u + 6.80
= 9 u + 6.80
9 u + 6.80 = 12.20
9 u = 12.20 - 6.80
9 u = 5.40
1 u = 5.40 ÷ 9 = 0.60
Cost of 1 marble
= 1 u + 1.70
= 0.60 + 1.70
= $2.30
(b)
Cost of 6 marbles
= 6 x 2.30
= $13.80
(c)
Cost of 1 bead and 6 marbles
= 0.60 + 13.80
= $14.40
(d)
Cost of 6 marbles more than 1 bead
= 13.80 - 0.60
= $13.20
Answer(s): (a) $2.30; (b) $13.80; (c) $14.40; (d) $13.20