Adam pays $25.60 for a marble, a bead and a sticker.
The marble costs $3.90 less than the bead.
The bead costs $1.60 less than the sticker.
What is the cost of 6 stickers more than 3 marbles?
Choose the cheapest item to be 1 u.

Cost of the marble = 1 u
Cost of the bead = 1 u + 3.90
Cost of the sticker = 1 u + 3.90 + 1.60 = 1 u + 5.50

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 3.90 + 1 u + 5.50
= 3 u + 9.40

3 u + 9.40 = 25.60
3 u = 25.60 - 9.40
3 u = 16.20

1 u = 16.20 ÷ 3 = 5.40

Cost of 6 stickers more than 3 marbles
= 6 x (1 u + 5.50) - 3 x 1 u
= 6 u + 33.00 - 3 u
= 3 u + 33.00
= 3 x 5.40 + 33.00
= 16.20 + 33.00
= $49.20

Answer(s): $49.20