Adam spends $12.90 on 3 marbles and 4 beads.
A marble costs $2.90 more than 1 bead.
- How much does 1 marble cost?
- How much do 5 marbles cost?
- How much do a bead and 5 marbles cost?
- How much do 5 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 + 2.90
Total cost of 3 marbles and 4 beads
= 3(1 u + 2.90) + 4 u
= 3 u + 8.70 + 4 u
= 3 u + 4 u + 8.70
= 7 u + 8.70
7 u + 8.70 = 12.90
7 u = 12.90 - 8.70
7 u = 4.20
1 u = 4.20 ÷ 7 = 0.60
Cost of 1 marble
= 1 u + 2.90
= 0.60 + 2.90
= $3.50
(b)
Cost of 5 marbles
= 5 x 3.50
= $17.50
(c)
Cost of 1 bead and 5 marbles
= 0.60 + 17.50
= $18.10
(d)
Cost of 5 marbles more than 1 bead
= 17.50 - 0.60
= $16.90
Answer(s): (a) $3.50; (b) $17.50; (c) $18.10; (d) $16.90
