If Adam buys 5 marbles and 6 beads, it costs $71.40.
If Adam buys 6 marbles and 5 beads, he will have $20 left.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
5 marbles + 6 beads = 71.40 --- (1)
6 marbles + 5 beads = 71.40 - 20 = 69.40 --- (2)
(1) + (2)
11 marbles + 11 beads = 140.80 --- (3)
(3)
÷ 11 1 marble + 1 bead = 140.80 ÷ 11 = 12.80 --- (4)
Cost of 1 marble and 1 bead = $12.80
(b)
(4)
x 5 5 marbles + 5 beads = 5 x 12.80 = 640 --- (5)
(2) - (5)
6 marbles + 5 beads - 5 marbles - 5 beads = 69.40 - 640
6 marbles - 5 marbles - 5 beads + 5 beads = 5.40
1 marble = 5.40
Cost of 1 marble = $5.40
(c)
Substitute 1 marble = 5.40 into (4).
1 marble + 1 bead = 12.80
5.40 + 1 bead = 12.80
1 bead = 12.80 - 5.40 = 7.40
Cost of 1 bead = $7.40
Answer(s): (a) $12.80; (b) $5.40; (c) $7.40