If Adam buys 4 marbles and 5 beads, it costs $68.40.
If Adam buys 5 marbles and 4 beads, he will have $3.60 left.
- 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 = 68.40 --- (1)
5 marbles + 4 beads = 68.40 - 3.60 = 64.80 --- (2)
(1) + (2)
9 marbles + 9 beads = 133.20 --- (3)
(3)
÷ 9 1 marble + 1 bead = 133.20 ÷ 9 = 14.80 --- (4)
Cost of 1 marble and 1 bead = $14.80
(b)
(4)
x 4 4 marbles + 4 beads = 4 x 14.80 = 59.20 --- (5)
(2) - (5)
5 marbles + 4 beads - 4 marbles - 4 beads = 64.80 - 59.20
5 marbles - 4 marbles - 4 beads + 4 beads = 5.60
1 marble = 5.60
Cost of 1 marble = $5.60
(c)
Substitute 1 marble = 5.60 into (4).
1 marble + 1 bead = 14.80
5.60 + 1 bead = 14.80
1 bead = 14.80 - 5.60 = 9.20
Cost of 1 bead = $9.20
Answer(s): (a) $14.80; (b) $5.60; (c) $9.20