Adam spends $15.70 on 2 marbles and 3 beads.
A marble costs $2.10 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 + 2.10
Total cost of 2 marbles and 3 beads
= 2(1 u + 2.10) + 3 u
= 2 u + 4.20 + 3 u
= 2 u + 3 u + 4.20
= 5 u + 4.20
5 u + 4.20 = 15.70
5 u = 15.70 - 4.20
5 u = 11.50
1 u = 11.50 ÷ 5 = 2.30
Cost of 1 marble
= 1 u + 2.10
= 2.30 + 2.10
= $4.40
(b)
Cost of 7 marbles
= 7 x 4.40
= $30.80
(c)
Cost of 1 bead and 7 marbles
= 2.30 + 30.80
= $33.10
(d)
Cost of 7 marbles more than 1 bead
= 30.80 - 2.30
= $28.50
Answer(s): (a) $4.40; (b) $30.80; (c) $33.10; (d) $28.50