If Adam buys 2 marbles and 3 beads, it costs $30.30.
If Adam buys 3 marbles and 2 beads, he will need another $1.90.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
2 marbles + 3 beads = 30.30 --- (1)
3 marbles + 2 beads = 30.30 + 1.90 = 32.20 --- (2)
(1) + (2)
5 marbles + 5 beads = 62.50 --- (3)
(3)
÷ 5 1 marble + 1 bead = 62.50 ÷ 5 = 12.50 --- (4)
Cost of 1 marble and 1 bead = $12.50
(b)
3 marbles + 2 beads = 32.20 --- (2)
(4)
x 2 2 marbles + 2 beads = 2 x 12.50 = 250 --- (5)
(2) - (5)
3 marbles + 2 beads - 2 marbles - 2 beads = 32.20 - 250
3 marbles - 2 marbles + 2 beads - 2 beads = 7.20
1 marble = 7.20
Cost of 1 marble = $7.20
(c)
Substitute 1 marble = 7.20 into (4).
1 marble + 1 bead = 12.50
7.20 + 1 bead = 12.50
1 bead = 12.50 - 7.20 = 5.30
Cost of 1 bead = $5.30
Answer(s): (a) $12.50; (b) $7.20; (c) $5.30