Adam spends $13.50 on 3 marbles and 4 beads.
A marble costs $1.70 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 + 1.70
Total cost of 3 marbles and 4 beads
= 3(1 u + 1.70) + 4 u
= 3 u + 5.10 + 4 u
= 3 u + 4 u + 5.10
= 7 u + 5.10
7 u + 5.10 = 13.50
7 u = 13.50 - 5.10
7 u = 8.40
1 u = 8.40 ÷ 7 = 1.20
Cost of 1 marble
= 1 u + 1.70
= 1.20 + 1.70
= $2.90
(b)
Cost of 4 marbles
= 4 x 2.90
= $11.60
(c)
Cost of 1 bead and 4 marbles
= 1.20 + 11.60
= $12.80
(d)
Cost of 4 marbles more than 1 bead
= 11.60 - 1.20
= $10.40
Answer(s): (a) $2.90; (b) $11.60; (c) $12.80; (d) $10.40