If Adam buys 4 marbles and 5 beads, it costs $45.60.
If Adam buys 5 marbles and 4 beads, he will need another $3.30.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
4 marbles + 5 beads = 45.60 --- (1)
5 marbles + 4 beads = 45.60 + 3.30 = 48.90 --- (2)
(1) + (2)
9 marbles + 9 beads = 94.50 --- (3)
(3)
÷ 9 1 marble + 1 bead = 94.50 ÷ 9 = 10.50 --- (4)
Cost of 1 marble and 1 bead = $10.50
(b)
5 marbles + 4 beads = 48.90 --- (2)
(4)
x 4 4 marbles + 4 beads = 4 x 10.50 = 420 --- (5)
(2) - (5)
5 marbles + 4 beads - 4 marbles - 4 beads = 48.90 - 420
5 marbles - 4 marbles + 4 beads - 4 beads = 6.90
1 marble = 6.90
Cost of 1 marble = $6.90
(c)
Substitute 1 marble = 6.90 into (4).
1 marble + 1 bead = 10.50
6.90 + 1 bead = 10.50
1 bead = 10.50 - 6.90 = 3.60
Cost of 1 bead = $3.60
Answer(s): (a) $10.50; (b) $6.90; (c) $3.60