Adam spends $13.10 on 3 marbles and 4 beads.
A marble costs $2.50 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 + 2.50
Total cost of 3 marbles and 4 beads
= 3(1 u + 2.50) + 4 u
= 3 u + 7.50 + 4 u
= 3 u + 4 u + 7.50
= 7 u + 7.50
7 u + 7.50 = 13.10
7 u = 13.10 - 7.50
7 u = 5.60
1 u = 5.60 ÷ 7 = 0.80
Cost of 1 marble
= 1 u + 2.50
= 0.80 + 2.50
= $3.30
(b)
Cost of 5 marbles
= 5 x 3.30
= $16.50
(c)
Cost of 1 bead and 5 marbles
= 0.80 + 16.50
= $17.30
(d)
Cost of 5 marbles more than 1 bead
= 16.50 - 0.80
= $15.70
Answer(s): (a) $3.30; (b) $16.50; (c) $17.30; (d) $15.70