If Adam buys 3 beads and 4 marbles, it costs $430.
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 = 430 --- (1)
4 beads + 3 marbles = 430 + 4.30 = 47.30 --- (2)
(1) + (2)
7 beads + 7 marbles = 90.30 --- (3)
(3)
÷ 7 1 bead + 1 marble = 90.30 ÷ 7 = 12.90 --- (4)
Cost of 1 bead and 1 marble = $12.90
(b)
4 beads + 3 marbles = 47.30 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 12.90 = 38.70 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 47.30 - 38.70
4 beads - 3 beads + 3 marbles - 3 marbles = 8.60
1 bead = 8.60
Cost of 1 bead = $8.60
(c)
Substitute 1 bead = 8.60 into (4).
1 bead + 1 marble = 12.90
8.60 + 1 marble = 12.90
1 marble = 12.90 - 8.60 = 4.30
Cost of 1 marble = $4.30
Answer(s): (a) $12.90; (b) $8.60; (c) $4.30