If Adam buys 3 beads and 4 marbles, it costs $35.70.
If Adam buys 4 beads and 3 marbles, he will need another $3.50.
- 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 = 35.70 --- (1)
4 beads + 3 marbles = 35.70 + 3.50 = 39.20 --- (2)
(1) + (2)
7 beads + 7 marbles = 74.90 --- (3)
(3)
÷ 7 1 bead + 1 marble = 74.90 ÷ 7 = 10.70 --- (4)
Cost of 1 bead and 1 marble = $10.70
(b)
4 beads + 3 marbles = 39.20 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 10.70 = 32.10 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 39.20 - 32.10
4 beads - 3 beads + 3 marbles - 3 marbles = 7.10
1 bead = 7.10
Cost of 1 bead = $7.10
(c)
Substitute 1 bead = 7.10 into (4).
1 bead + 1 marble = 10.70
7.10 + 1 marble = 10.70
1 marble = 10.70 - 7.10 = 3.60
Cost of 1 marble = $3.60
Answer(s): (a) $10.70; (b) $7.10; (c) $3.60