A marble, a bead and a sticker costs $7.60 altogether.
The marble costs $1.20 less than the bead.
The sticker costs $2.50 more than the bead.
How much do 2 stickers cost?
Choose the cheapest item to be 1 u.
The marble costs $1.20 less than the bead.
The cheapest item is the marble.

Cost of the marble = 1 u
Cost of the bead = 1 u + 1.20
Cost of the sticker = 1 u + 1.20 + 2.50 = 1 u + 3.70

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 1.20 + 1 u + 3.70
= 1 u + 1 u + 1 u + 1.20 + 3.70
= 3 u + 4.9

3 u + 4.90 = 7.60
3 u = 7.60 - 4.90
3 u = 2.70

1 u = 2.70 ÷ 3 = 0.90

Cost of 2 stickers
= 2 x (1 u + 3.70)
= 2 x (0.90 + 3.70)
= 2 x 4.60
= $9.20

Answer(s): $9.20