If Adam buys 3 beads and 4 marbles, it costs $32.60.
If Adam buys 4 beads and 3 marbles, he will need another $3.40.
- 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 = 32.60 --- (1)
4 beads + 3 marbles = 32.60 + 3.40 = 360 --- (2)
(1) + (2)
7 beads + 7 marbles = 68.60 --- (3)
(3)
÷ 7 1 bead + 1 marble = 68.60 ÷ 7 = 9.80 --- (4)
Cost of 1 bead and 1 marble = $9.80
(b)
4 beads + 3 marbles = 360 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 9.80 = 29.40 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 360 - 29.40
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 = 9.80
6.60 + 1 marble = 9.80
1 marble = 9.80 - 6.60 = 3.20
Cost of 1 marble = $3.20
Answer(s): (a) $9.80; (b) $6.60; (c) $3.20