If Adam buys 3 beads and 4 marbles, it costs $360.
If Adam buys 4 beads and 3 marbles, he will need another $4.30.
- 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 = 360 --- (1)
4 beads + 3 marbles = 360 + 4.30 = 40.30 --- (2)
(1) + (2)
7 beads + 7 marbles = 76.30 --- (3)
(3)
÷ 7 1 bead + 1 marble = 76.30 ÷ 7 = 10.90 --- (4)
Cost of 1 bead and 1 marble = $10.90
(b)
4 beads + 3 marbles = 40.30 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 10.90 = 32.70 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 40.30 - 32.70
4 beads - 3 beads + 3 marbles - 3 marbles = 7.60
1 bead = 7.60
Cost of 1 bead = $7.60
(c)
Substitute 1 bead = 7.60 into (4).
1 bead + 1 marble = 10.90
7.60 + 1 marble = 10.90
1 marble = 10.90 - 7.60 = 3.30
Cost of 1 marble = $3.30
Answer(s): (a) $10.90; (b) $7.60; (c) $3.30