Adam spends $12.70 on 2 marbles and 3 beads.
A marble costs $2.10 more than 1 bead.
- How much does 1 marble cost?
- How much do 8 marbles cost?
- How much do a bead and 8 marbles cost?
- How much do 8 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 = 12.70
5 u = 12.70 - 4.20
5 u = 8.50
1 u = 8.50 ÷ 5 = 1.70
Cost of 1 marble
= 1 u + 2.10
= 1.70 + 2.10
= $3.80
(b)
Cost of 8 marbles
= 8 x 3.80
= $30.40
(c)
Cost of 1 bead and 8 marbles
= 1.70 + 30.40
= $32.10
(d)
Cost of 8 marbles more than 1 bead
= 30.40 - 1.70
= $28.70
Answer(s): (a) $3.80; (b) $30.40; (c) $32.10; (d) $28.70