If Adam buys 4 marbles and 5 beads, it costs $50.10.
If Adam buys 5 marbles and 4 beads, he will need another $4.20.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
4 marbles + 5 beads = 50.10 --- (1)
5 marbles + 4 beads = 50.10 + 4.20 = 54.30 --- (2)
(1) + (2)
9 marbles + 9 beads = 104.40 --- (3)
(3)
÷ 9 1 marble + 1 bead = 104.40 ÷ 9 = 11.60 --- (4)
Cost of 1 marble and 1 bead = $11.60
(b)
5 marbles + 4 beads = 54.30 --- (2)
(4)
x 4 4 marbles + 4 beads = 4 x 11.60 = 46.40 --- (5)
(2) - (5)
5 marbles + 4 beads - 4 marbles - 4 beads = 54.30 - 46.40
5 marbles - 4 marbles + 4 beads - 4 beads = 7.90
1 marble = 7.90
Cost of 1 marble = $7.90
(c)
Substitute 1 marble = 7.90 into (4).
1 marble + 1 bead = 11.60
7.90 + 1 bead = 11.60
1 bead = 11.60 - 7.90 = 3.70
Cost of 1 bead = $3.70
Answer(s): (a) $11.60; (b) $7.90; (c) $3.70