Adam spends $14.50 on 3 marbles and 4 beads.
A marble costs $1.80 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 + 1.80
Total cost of 3 marbles and 4 beads
= 3(1 u + 1.80) + 4 u
= 3 u + 5.40 + 4 u
= 3 u + 4 u + 5.40
= 7 u + 5.40
7 u + 5.40 = 14.50
7 u = 14.50 - 5.40
7 u = 9.10
1 u = 9.10 ÷ 7 = 1.30
Cost of 1 marble
= 1 u + 1.80
= 1.30 + 1.80
= $3.10
(b)
Cost of 4 marbles
= 4 x 3.10
= $12.40
(c)
Cost of 1 bead and 4 marbles
= 1.30 + 12.40
= $13.70
(d)
Cost of 4 marbles more than 1 bead
= 12.40 - 1.30
= $11.10
Answer(s): (a) $3.10; (b) $12.40; (c) $13.70; (d) $11.10