Adam spends $12.20 on 4 marbles and 5 beads.
A marble costs $2.60 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 + 2.60
Total cost of 4 marbles and 5 beads
= 4(1 u + 2.60) + 5 u
= 4 u + 10.40 + 5 u
= 4 u + 5 u + 10.40
= 9 u + 10.40
9 u + 10.40 = 12.20
9 u = 12.20 - 10.40
9 u = 1.80
1 u = 1.80 ÷ 9 = 0.20
Cost of 1 marble
= 1 u + 2.60
= 0.20 + 2.60
= $2.80
(b)
Cost of 7 marbles
= 7 x 2.80
= $19.60
(c)
Cost of 1 bead and 7 marbles
= 0.20 + 19.60
= $19.80
(d)
Cost of 7 marbles more than 1 bead
= 19.60 - 0.20
= $19.40
Answer(s): (a) $2.80; (b) $19.60; (c) $19.80; (d) $19.40
