If Adam buys 4 marbles and 5 beads, it costs $51.30.
If Adam buys 5 marbles and 4 beads, he will need another $3.60.

1. Find the cost of 1 marble and 1 bead.
2. Find the cost of 1 marble.
3. Find the cost of 1 bead.

(a)
4 marbles + 5 beads = 51.30 --- (1)
5 marbles + 4 beads = 51.30 + 3.60 = 54.90 --- (2)

(1) + (2)
9 marbles + 9 beads = 106.20 --- (3)

(3) _{÷ 9}
1 marble + 1 bead = 106.20 ÷ 9 = 11.80 --- (4)

Cost of 1 marble and 1 bead = $11.80

(b)
5 marbles + 4 beads = 54.90 --- (2)

(4) _{x 4}
4 marbles + 4 beads = 4 x 11.80 = 47.20 --- (5)

(2) - (5)
5 marbles + 4 beads - 4 marbles - 4 beads = 54.90 - 47.20
5 marbles - 4 marbles + 4 beads - 4 beads = 7.70
1 marble = 7.70

Cost of 1 marble = $7.70

(c)
Substitute 1 marble = 7.70 into (4).

1 marble + 1 bead = 11.80
7.70 + 1 bead = 11.80
1 bead = 11.80 - 7.70 = 4.10

Cost of 1 bead = $4.10

Answer(s): (a) $11.80; (b) $7.70; (c) $4.10