3 beads and 1 marble cost $7.50.
1 bead and 3 marbles cost $11.30.
- 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 6 beads and 6 marbles.
(a)
3 beads + 1 marble = 7.50 --- (1)
1 bead + 3 marbles = 11.30 --- (2)
(1) + (2)
4 beads + 4 marbles = 7.50 + 11.30
4 beads + 4 marbles = 18.80 --- (3)
(3)
÷ 44 beads + 4 marbles = 18.80
1 bead + 1 marble = 18.80 ÷ 4
1 bead + 1 marble = 4.70 --- (4)
(b)
(2) - (4)
(1 bead + 3 marbles) - (1 bead + 1 marble) = 11.30 - 4.70
1 bead - 1 bead + 3 marbles - 1 marble = 6.60
2 marbles = 6.60
1 marble = 6.60 ÷ 2 = 3.30
Cost of 1 marble = $3.30
(c)
Substitute 1 marble = 3.30 into (4).
1 bead + 1 marble = 4.70
1 bead + 3.30 = 4.70
1 bead = 4.70 - 3.30 = 1.40
Cost of 1 bead = $1.40
(d)
(4)
x 6 1 bead + 1 marble = 4.70
6 x (1 bead + 1 marble) = 6 x 4.70
6 beads + 6 marbles = 28.20
Cost of 6 beads and 6 marbles = $28.20
Answer(s): (a) $4.70; (b) $3.30; (c) $1.40; (d) $28.20