2 stickers and 1 bead cost $10.70.
1 sticker and 2 beads cost $8.50.

1. Find the cost of 1 sticker and 1 bead.
2. Find the cost of 1 bead.
3. Find the cost of 1 sticker.
4. Find the cost of 4 stickers and 4 beads.

(a)
2 stickers + 1 bead = 10.70 --- (1)
1 sticker + 2 beads = 8.50 --- (2)

(1) + (2)
3 stickers + 3 beads = 10.70 + 8.50
3 stickers + 3 beads = 19.20 --- (3)

(3) _{÷ 3}
3 stickers + 3 beads = 19.20
1 sticker + 1 bead = 19.20 ÷ 3 
1 sticker + 1 bead = 6.40 --- (4)

Cost of 1 sticker and 1 bead = $6.40

(b)
(2) - (4)
(1 sticker + 2 beads) - (1 sticker + 1 marble) = 8.50 - 6.40
1 sticker - 1 sticker + 2 beads - 1 bead = 2.10
1 bead = 2.10

Cost of 1 bead = $2.10

(c)
Substitute 1 bead = 2.10 into (4).
1 sticker + 1 bead = 6.40
1 sticker + 2.10 = 6.40
1 sticker = 6.40 - 2.10 = 4.30

Cost of 1 sticker = $4.30

(d)
(4) _{x 4}
1 sticker + 1 bead = 6.40
4 x (1 sticker + 1 marble) = 4 x 6.40
4 stickers + 4 beads = 25.60

Cost of 4 stickers and 4 beads = $25.60

Answer(s): (a) $6.40; (b) $2.10; (c) $4.30; (d) $25.60