4 beads and 1 marble cost $15.60.
1 bead and 4 marbles cost $12.90.
- 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 5 beads and 5 marbles.
(a)
4 beads + 1 marble = 15.60 --- (1)
1 bead + 4 marbles = 12.90 --- (2)
(1) + (2)
5 beads + 5 marbles = 15.60 + 12.90
5 beads + 5 marbles = 28.50 --- (3)
(3)
÷ 55 beads + 5 marbles = 28.50
1 bead + 1 marble = 28.50 ÷ 5
1 bead + 1 marble = 5.70 --- (4)
(b)
(2) - (4)
(1 bead + 4 marbles) - (1 bead + 1 marble) = 12.90 - 5.70
1 bead - 1 bead + 4 marbles - 1 marble = 7.20
3 marbles = 7.20
1 marble = 7.20 ÷ 3 = 2.40
Cost of 1 marble = $2.40
(c)
Substitute 1 marble = 2.40 into (4).
1 bead + 1 marble = 5.70
1 bead + 2.40 = 5.70
1 bead = 5.70 - 2.40 = 3.30
Cost of 1 bead = $3.30
(d)
(4)
x 5 1 bead + 1 marble = 5.70
5 x (1 bead + 1 marble) = 5 x 5.70
5 beads + 5 marbles = 28.50
Cost of 5 beads and 5 marbles = $28.50
Answer(s): (a) $5.70; (b) $2.40; (c) $3.30; (d) $28.50