A marble, a bead and a sticker costs $9.20 altogether.
The marble costs $3.70 less than the bead.
The sticker costs $1.20 more than the bead.
How much do 2 stickers cost?
Choose the cheapest item to be 1 u.
The marble costs $3.70 less than the bead.
The cheapest item is the marble.

Cost of the marble = 1 u
Cost of the bead = 1 u + 3.70
Cost of the sticker = 1 u + 3.70 + 1.20 = 1 u + 4.90

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 3.70 + 1 u + 4.90
= 1 u + 1 u + 1 u + 3.70 + 4.90
= 3 u + 8.6

3 u + 8.60 = 9.20
3 u = 9.20 - 8.60
3 u = 0.60

1 u = 0.60 ÷ 3 = 0.20

Cost of 2 stickers
= 2 x (1 u + 4.90)
= 2 x (0.20 + 4.90)
= 2 x 5.10
= $10.20

Answer(s): $10.20