4 marbles and 1 bead cost $15.70.
1 marble and 4 beads cost $14.80.

1. Find the cost of 1 marble and 1 bead.
2. Find the cost of 1 bead.
3. Find the cost of 1 marble.
4. Find the cost of 6 marbles and 6 beads.

(a)
4 marbles + 1 bead = 15.70 --- (1)
1 marble + 4 beads = 14.80 --- (2)

(1) + (2)
5 marbles + 5 beads = 15.70 + 14.80
5 marbles + 5 beads = 30.50 --- (3)

(3) _{÷ 5}
5 marbles + 5 beads = 30.50
1 marble + 1 bead = 30.50 ÷ 5
1 marble + 1 bead = 6.10 --- (4)

(b)
(2) - (4)
(1 marble + 4 beads) - (1 marble + 1 marble) = 14.80 - 6.10
1 marble - 1 marble + 4 beads - 1 bead = 8.70
3 beads = 8.70
1 bead = 8.70 ÷ 3 = 2.90

Cost of 1 bead = $2.90

(c)
Substitute 1 bead = 2.90 into (4).
1 marble + 1 bead = 6.10
1 marble + 2.90 = 6.10
1 marble = 6.10 - 2.90 = 3.20

Cost of 1 marble = $3.20

(d)
(4) _{x 6}
1 marble + 1 bead = 6.10
6 x (1 marble + 1 marble) = 6 x 6.10
6 marbles + 6 beads = 36.60

Cost of 6 marbles and 6 beads = $36.60

Answer(s): (a) $6.10; (b) $2.90; (c) $3.20; (d) $36.60