If Adam buys 3 marbles and 4 beads, it costs $44.30.
If Adam buys 4 marbles and 3 beads, he will need another $4.50.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
3 marbles + 4 beads = 44.30 --- (1)
4 marbles + 3 beads = 44.30 + 4.50 = 48.80 --- (2)
(1) + (2)
7 marbles + 7 beads = 93.10 --- (3)
(3)
÷ 7 1 marble + 1 bead = 93.10 ÷ 7 = 13.30 --- (4)
Cost of 1 marble and 1 bead = $13.30
(b)
4 marbles + 3 beads = 48.80 --- (2)
(4)
x 3 3 marbles + 3 beads = 3 x 13.30 = 39.90 --- (5)
(2) - (5)
4 marbles + 3 beads - 3 marbles - 3 beads = 48.80 - 39.90
4 marbles - 3 marbles + 3 beads - 3 beads = 8.90
1 marble = 8.90
Cost of 1 marble = $8.90
(c)
Substitute 1 marble = 8.90 into (4).
1 marble + 1 bead = 13.30
8.90 + 1 bead = 13.30
1 bead = 13.30 - 8.90 = 4.40
Cost of 1 bead = $4.40
Answer(s): (a) $13.30; (b) $8.90; (c) $4.40