5 beads and 1 marble cost $23.20.
1 bead and 5 marbles cost $22.40.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
- Find the cost of 4 beads and 4 marbles.
(a)
5 beads + 1 marble = 23.20 --- (1)
1 bead + 5 marbles = 22.40 --- (2)
(1) + (2)
6 beads + 6 marbles = 23.20 + 22.40
6 beads + 6 marbles = 45.60 --- (3)
(3)
÷ 66 beads + 6 marbles = 45.60
1 bead + 1 marble = 45.60 ÷ 6
1 bead + 1 marble = 7.60 --- (4)
(b)
(2) - (4)
(1 bead + 5 marbles) - (1 bead + 1 marble) = 22.40 - 7.60
1 bead - 1 bead + 5 marbles - 1 marble = 14.80
4 marbles = 14.80
1 marble = 14.80 ÷ 4 = 3.70
Cost of 1 marble = $3.70
(c)
Substitute 1 marble = 3.70 into (4).
1 bead + 1 marble = 7.60
1 bead + 3.70 = 7.60
1 bead = 7.60 - 3.70 = 3.90
Cost of 1 bead = $3.90
(d)
(4)
x 4 1 bead + 1 marble = 7.60
4 x (1 bead + 1 marble) = 4 x 7.60
4 beads + 4 marbles = 30.40
Cost of 4 beads and 4 marbles = $30.40
Answer(s): (a) $7.60; (b) $3.70; (c) $3.90; (d) $30.40