If Adam buys 4 beads and 5 marbles, it costs $56.40.
If Adam buys 5 beads and 4 marbles, he will need another $2.40.
- 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 = 56.40 --- (1)
5 beads + 4 marbles = 56.40 + 2.40 = 58.80 --- (2)
(1) + (2)
9 beads + 9 marbles = 115.20 --- (3)
(3)
÷ 9 1 bead + 1 marble = 115.20 ÷ 9 = 12.80 --- (4)
Cost of 1 bead and 1 marble = $12.80
(b)
5 beads + 4 marbles = 58.80 --- (2)
(4)
x 4 4 beads + 4 marbles = 4 x 12.80 = 51.20 --- (5)
(2) - (5)
5 beads + 4 marbles - 4 beads - 4 marbles = 58.80 - 51.20
5 beads - 4 beads + 4 marbles - 4 marbles = 7.60
1 bead = 7.60
Cost of 1 bead = $7.60
(c)
Substitute 1 bead = 7.60 into (4).
1 bead + 1 marble = 12.80
7.60 + 1 marble = 12.80
1 marble = 12.80 - 7.60 = 5.20
Cost of 1 marble = $5.20
Answer(s): (a) $12.80; (b) $7.60; (c) $5.20