If Adam buys 3 beads and 4 marbles, it costs $40.20.
If Adam buys 4 beads and 3 marbles, he will need another $1.50.
- 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 = 40.20 --- (1)
4 beads + 3 marbles = 40.20 + 1.50 = 41.70 --- (2)
(1) + (2)
7 beads + 7 marbles = 81.90 --- (3)
(3)
÷ 7 1 bead + 1 marble = 81.90 ÷ 7 = 11.70 --- (4)
Cost of 1 bead and 1 marble = $11.70
(b)
4 beads + 3 marbles = 41.70 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 11.70 = 35.10 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 41.70 - 35.10
4 beads - 3 beads + 3 marbles - 3 marbles = 6.60
1 bead = 6.60
Cost of 1 bead = $6.60
(c)
Substitute 1 bead = 6.60 into (4).
1 bead + 1 marble = 11.70
6.60 + 1 marble = 11.70
1 marble = 11.70 - 6.60 = 5.10
Cost of 1 marble = $5.10
Answer(s): (a) $11.70; (b) $6.60; (c) $5.10