Adam spends $14.70 on 3 marbles and 4 beads.
A marble costs $2.80 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 + 2.80
Total cost of 3 marbles and 4 beads
= 3(1 u + 2.80) + 4 u
= 3 u + 8.40 + 4 u
= 3 u + 4 u + 8.40
= 7 u + 8.40
7 u + 8.40 = 14.70
7 u = 14.70 - 8.40
7 u = 6.30
1 u = 6.30 ÷ 7 = 0.90
Cost of 1 marble
= 1 u + 2.80
= 0.90 + 2.80
= $3.70
(b)
Cost of 4 marbles
= 4 x 3.70
= $14.80
(c)
Cost of 1 bead and 4 marbles
= 0.90 + 14.80
= $15.70
(d)
Cost of 4 marbles more than 1 bead
= 14.80 - 0.90
= $13.90
Answer(s): (a) $3.70; (b) $14.80; (c) $15.70; (d) $13.90