2 beads and 1 marble cost $11.30.
1 bead and 2 marbles cost $11.50.

1. Find the cost of 1 bead and 1 marble.
2. Find the cost of 1 marble.
3. Find the cost of 1 bead.
4. Find the cost of 4 beads and 4 marbles.

(a)
2 beads + 1 marble = 11.30 --- (1)
1 bead + 2 marbles = 11.50 --- (2)

(1) + (2)
3 beads + 3 marbles = 11.30 + 11.50
3 beads + 3 marbles = 22.80 --- (3)

(3) _{÷ 3}
3 beads + 3 marbles = 22.80
1 bead + 1 marble = 22.80 ÷ 3 
1 bead + 1 marble = 7.60 --- (4)

Cost of 1 bead and 1 marble = $7.60

(b)
(2) - (4)
(1 bead + 2 marbles) - (1 bead + 1 marble) = 11.50 - 7.60
1 bead - 1 bead + 2 marbles - 1 marble = 3.90
1 marble = 3.90

Cost of 1 marble = $3.90

(c)
Substitute 1 marble = 3.90 into (4).
1 bead + 1 marble = 7.60
1 bead + 3.90 = 7.60
1 bead = 7.60 - 3.90 = 3.70

Cost of 1 bead = $3.70

(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) $3.90; (c) $3.70; (d) $30.40