A sticker, a marble and a bead costs $9.80 altogether.
The sticker costs $2.30 less than the marble.
The bead costs $1.30 more than the marble.
How much do 2 beads cost?
Choose the cheapest item to be 1 u.
The sticker costs $2.30 less than the marble.
The cheapest item is the sticker.

Cost of the sticker = 1 u
Cost of the marble = 1 u + 2.30
Cost of the bead = 1 u + 2.30 + 1.30 = 1 u + 3.60

Total cost of the sticker, the marble and the bead
= 1 u + 1 u + 2.30 + 1 u + 3.60
= 1 u + 1 u + 1 u + 2.30 + 3.60
= 3 u + 5.9

3 u + 5.90 = 9.80
3 u = 9.80 - 5.90
3 u = 3.90

1 u = 3.90 ÷ 3 = 1.30

Cost of 2 beads
= 2 x (1 u + 3.60)
= 2 x (1.30 + 3.60)
= 2 x 4.90
= $9.80

Answer(s): $9.80