If Adam buys 4 beads and 5 marbles, it costs $56.60.
If Adam buys 5 beads and 4 marbles, he will need another $1.10.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 bead.
- Find the cost of 1 marble.
(a)
4 beads + 5 marbles = 56.60 --- (1)
5 beads + 4 marbles = 56.60 + 1.10 = 57.70 --- (2)
(1) + (2)
9 beads + 9 marbles = 114.30 --- (3)
(3)
÷ 9 1 bead + 1 marble = 114.30 ÷ 9 = 12.70 --- (4)
Cost of 1 bead and 1 marble = $12.70
(b)
5 beads + 4 marbles = 57.70 --- (2)
(4)
x 4 4 beads + 4 marbles = 4 x 12.70 = 50.80 --- (5)
(2) - (5)
5 beads + 4 marbles - 4 beads - 4 marbles = 57.70 - 50.80
5 beads - 4 beads + 4 marbles - 4 marbles = 6.90
1 bead = 6.90
Cost of 1 bead = $6.90
(c)
Substitute 1 bead = 6.90 into (4).
1 bead + 1 marble = 12.70
6.90 + 1 marble = 12.70
1 marble = 12.70 - 6.90 = 5.80
Cost of 1 marble = $5.80
Answer(s): (a) $12.70; (b) $6.90; (c) $5.80