2 beads and 1 sticker cost $12.10.
1 bead and 2 stickers cost $11.30.

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

(a)
2 beads + 1 sticker = 12.10 --- (1)
1 bead + 2 stickers = 11.30 --- (2)

(1) + (2)
3 beads + 3 stickers = 12.10 + 11.30
3 beads + 3 stickers = 23.40 --- (3)

(3) _{÷ 3}
3 beads + 3 stickers = 23.40
1 bead + 1 sticker = 23.40 ÷ 3 
1 bead + 1 sticker = 7.80 --- (4)

Cost of 1 bead and 1 sticker = $7.80

(b)
(2) - (4)
(1 bead + 2 stickers) - (1 bead + 1 marble) = 11.30 - 7.80
1 bead - 1 bead + 2 stickers - 1 sticker = 3.50
1 sticker = 3.50

Cost of 1 sticker = $3.50

(c)
Substitute 1 sticker = 3.50 into (4).
1 bead + 1 sticker = 7.80
1 bead + 3.50 = 7.80
1 bead = 7.80 - 3.50 = 4.30

Cost of 1 bead = $4.30

(d)
(4) _{x 4}
1 bead + 1 sticker = 7.80
4 x (1 bead + 1 marble) = 4 x 7.80
4 beads + 4 stickers = 31.20

Cost of 4 beads and 4 stickers = $31.20

Answer(s): (a) $7.80; (b) $3.50; (c) $4.30; (d) $31.20