2 beads and 1 marble cost $3.60.
1 bead and 2 marbles cost $3.60.
- 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)
2 beads + 1 marble = 3.60 --- (1)
1 bead + 2 marbles = 3.60 --- (2)
(1) + (2)
3 beads + 3 marbles = 3.60 + 3.60
3 beads + 3 marbles = 7.20 --- (3)
(3)
÷ 3
3 beads + 3 marbles = 7.20
1 bead + 1 marble = 7.20 ÷ 3
1 bead + 1 marble = 2.40 --- (4)
Cost of 1 bead and 1 marble = $2.40
(b)
(2) - (4)
(1 bead + 2 marbles) - (1 bead + 1 marble) = 3.60 - 2.40
1 bead - 1 bead + 2 marbles - 1 marble = 1.20
1 marble = 1.20
Cost of 1 marble = $1.20
(c)
Substitute 1 marble = 1.20 into (4).
1 bead + 1 marble = 2.40
1 bead + 1.20 = 2.40
1 bead = 2.40 - 1.20 = 1.20
Cost of 1 bead = $1.20
(d)
(4)
x 4 1 bead + 1 marble = 2.40
4 x (1 bead + 1 marble) = 4 x 2.40
4 beads + 4 marbles = 9.60
Cost of 4 beads and 4 marbles = $9.60
Answer(s): (a) $2.40; (b) $1.20; (c) $1.20; (d) $9.60