A sticker, a marble and a bead costs $9.80 altogether.
The sticker costs $1.50 less than the marble.
The bead costs $4.70 more than the marble.
How much do 4 beads cost?
Choose the cheapest item to be 1 u.
The sticker costs $1.50 less than the marble.
The cheapest item is the sticker.

Cost of the sticker = 1 u
Cost of the marble = 1 u + 1.50
Cost of the bead = 1 u + 1.50 + 4.70 = 1 u + 6.20

Total cost of the sticker, the marble and the bead
= 1 u + 1 u + 1.50 + 1 u + 6.20
= 1 u + 1 u + 1 u + 1.50 + 6.20
= 3 u + 7.7

3 u + 7.70 = 9.80
3 u = 9.80 - 7.70
3 u = 2.10

1 u = 2.10 ÷ 3 = 0.70

Cost of 4 beads
= 4 x (1 u + 6.20)
= 4 x (0.70 + 6.20)
= 4 x 6.90
= $27.60

Answer(s): $27.60