Adam spends $15.10 on 3 marbles and 4 beads.
A marble costs $1.30 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 + 1.30
Total cost of 3 marbles and 4 beads
= 3(1 u + 1.30) + 4 u
= 3 u + 3.90 + 4 u
= 3 u + 4 u + 3.90
= 7 u + 3.90
7 u + 3.90 = 15.10
7 u = 15.10 - 3.90
7 u = 11.20
1 u = 11.20 ÷ 7 = 1.60
Cost of 1 marble
= 1 u + 1.30
= 1.60 + 1.30
= $2.90
(b)
Cost of 7 marbles
= 7 x 2.90
= $20.30
(c)
Cost of 1 bead and 7 marbles
= 1.60 + 20.30
= $21.90
(d)
Cost of 7 marbles more than 1 bead
= 20.30 - 1.60
= $18.70
Answer(s): (a) $2.90; (b) $20.30; (c) $21.90; (d) $18.70