A marble, a sticker and a bead costs $9.30 altogether.
The marble costs $1.30 less than the sticker.
The bead costs $3.10 more than the sticker.
How much do 2 beads cost?
Choose the cheapest item to be 1 u.
The marble costs $1.30 less than the sticker.
The cheapest item is the marble.

Cost of the marble = 1 u
Cost of the sticker = 1 u + 1.30
Cost of the bead = 1 u + 1.30 + 3.10 = 1 u + 4.40

Total cost of the marble, the sticker and the bead
= 1 u + 1 u + 1.30 + 1 u + 4.40
= 1 u + 1 u + 1 u + 1.30 + 4.40
= 3 u + 5.7

3 u + 5.70 = 9.30
3 u = 9.30 - 5.70
3 u = 3.60

1 u = 3.60 ÷ 3 = 1.20

Cost of 2 beads
= 2 x (1 u + 4.40)
= 2 x (1.20 + 4.40)
= 2 x 5.60
= $11.20

Answer(s): $11.20