If Adam buys 3 beads and 4 marbles, it costs $45.70.
If Adam buys 4 beads and 3 marbles, he will need another $3.10.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 bead.
- Find the cost of 1 marble.
(a)
3 beads + 4 marbles = 45.70 --- (1)
4 beads + 3 marbles = 45.70 + 3.10 = 48.80 --- (2)
(1) + (2)
7 beads + 7 marbles = 94.50 --- (3)
(3)
÷ 7 1 bead + 1 marble = 94.50 ÷ 7 = 13.50 --- (4)
Cost of 1 bead and 1 marble = $13.50
(b)
4 beads + 3 marbles = 48.80 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 13.50 = 40.50 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 48.80 - 40.50
4 beads - 3 beads + 3 marbles - 3 marbles = 8.30
1 bead = 8.30
Cost of 1 bead = $8.30
(c)
Substitute 1 bead = 8.30 into (4).
1 bead + 1 marble = 13.50
8.30 + 1 marble = 13.50
1 marble = 13.50 - 8.30 = 5.20
Cost of 1 marble = $5.20
Answer(s): (a) $13.50; (b) $8.30; (c) $5.20