If Adam buys 3 beads and 4 marbles, it costs $45.60.
If Adam buys 4 beads and 3 marbles, he will need another $1.90.
- 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 = 45.60 --- (1)
4 beads + 3 marbles = 45.60 + 1.90 = 47.50 --- (2)
(1) + (2)
7 beads + 7 marbles = 93.10 --- (3)
(3)
÷ 7 1 bead + 1 marble = 93.10 ÷ 7 = 13.30 --- (4)
Cost of 1 bead and 1 marble = $13.30
(b)
4 beads + 3 marbles = 47.50 --- (2)
(4)
x 3 3 beads + 3 marbles = 3 x 13.30 = 39.90 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 47.50 - 39.90
4 beads - 3 beads + 3 marbles - 3 marbles = 7.60
1 bead = 7.60
Cost of 1 bead = $7.60
(c)
Substitute 1 bead = 7.60 into (4).
1 bead + 1 marble = 13.30
7.60 + 1 marble = 13.30
1 marble = 13.30 - 7.60 = 5.70
Cost of 1 marble = $5.70
Answer(s): (a) $13.30; (b) $7.60; (c) $5.70