If Adam buys 4 beads and 5 marbles, it costs $53.70.
If Adam buys 5 beads and 4 marbles, he will need another $4.20.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 bead.
- Find the cost of 1 marble.
(a)
4 beads + 5 marbles = 53.70 --- (1)
5 beads + 4 marbles = 53.70 + 4.20 = 57.90 --- (2)
(1) + (2)
9 beads + 9 marbles = 111.60 --- (3)
(3)
÷ 9 1 bead + 1 marble = 111.60 ÷ 9 = 12.40 --- (4)
Cost of 1 bead and 1 marble = $12.40
(b)
5 beads + 4 marbles = 57.90 --- (2)
(4)
x 4 4 beads + 4 marbles = 4 x 12.40 = 49.60 --- (5)
(2) - (5)
5 beads + 4 marbles - 4 beads - 4 marbles = 57.90 - 49.60
5 beads - 4 beads + 4 marbles - 4 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 = 12.40
8.30 + 1 marble = 12.40
1 marble = 12.40 - 8.30 = 4.10
Cost of 1 marble = $4.10
Answer(s): (a) $12.40; (b) $8.30; (c) $4.10