If Adam buys 3 beads and 4 marbles, it costs $390.
If Adam buys 4 beads and 3 marbles, he will need another $4.60.
- 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 = 390 --- (1)
4 beads + 3 marbles = 390 + 4.60 = 43.60 --- (2)
(1) + (2)
7 beads + 7 marbles = 82.60 --- (3)
(3)
÷ 7 1 bead + 1 marble = 82.60 ÷ 7 = 11.80 --- (4)
Cost of 1 bead and 1 marble = $11.80
(b)
4 beads + 3 marbles = 43.60 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 11.80 = 35.40 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 43.60 - 35.40
4 beads - 3 beads + 3 marbles - 3 marbles = 8.20
1 bead = 8.20
Cost of 1 bead = $8.20
(c)
Substitute 1 bead = 8.20 into (4).
1 bead + 1 marble = 11.80
8.20 + 1 marble = 11.80
1 marble = 11.80 - 8.20 = 3.60
Cost of 1 marble = $3.60
Answer(s): (a) $11.80; (b) $8.20; (c) $3.60