4 beads and 1 sticker cost $9.60.
1 bead and 4 stickers cost $15.90.

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)
4 beads + 1 sticker = 9.60 --- (1)
1 bead + 4 stickers = 15.90 --- (2)

(1) + (2)
5 beads + 5 stickers = 9.60 + 15.90
5 beads + 5 stickers = 25.50 --- (3)

(3) _{÷ 5}
5 beads + 5 stickers = 25.50
1 bead + 1 sticker = 25.50 ÷ 5
1 bead + 1 sticker = 5.10 --- (4)

(b)
(2) - (4)
(1 bead + 4 stickers) - (1 bead + 1 marble) = 15.90 - 5.10
1 bead - 1 bead + 4 stickers - 1 sticker = 10.80
3 stickers = 10.80
1 sticker = 10.80 ÷ 3 = 3.60

Cost of 1 sticker = $3.60

(c)
Substitute 1 sticker = 3.60 into (4).
1 bead + 1 sticker = 5.10
1 bead + 3.60 = 5.10
1 bead = 5.10 - 3.60 = 1.50

Cost of 1 bead = $1.50

(d)
(4) _{x 4}
1 bead + 1 sticker = 5.10
4 x (1 bead + 1 marble) = 4 x 5.10
4 beads + 4 stickers = 20.40

Cost of 4 beads and 4 stickers = $20.40

Answer(s): (a) $5.10; (b) $3.60; (c) $1.50; (d) $20.40