Adam spends $13.90 on 5 marbles and 6 beads.
A marble costs $1.90 more than 1 bead.
- How much does 1 marble cost?
- How much do 7 marbles cost?
- How much do a bead and 7 marbles cost?
- How much do 7 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 + 1.90
Total cost of 5 marbles and 6 beads
= 5(1 u + 1.90) + 6 u
= 5 u + 9.50 + 6 u
= 5 u + 6 u + 9.50
= 11 u + 9.50
11 u + 9.50 = 13.90
11 u = 13.90 - 9.50
11 u = 4.40
1 u = 4.40 ÷ 11 = 0.40
Cost of 1 marble
= 1 u + 1.90
= 0.40 + 1.90
= $2.30
(b)
Cost of 7 marbles
= 7 x 2.30
= $16.10
(c)
Cost of 1 bead and 7 marbles
= 0.40 + 16.10
= $16.50
(d)
Cost of 7 marbles more than 1 bead
= 16.10 - 0.40
= $15.70
Answer(s): (a) $2.30; (b) $16.10; (c) $16.50; (d) $15.70