Adam pays $26.50 for a marble, a bead and a sticker.
The marble costs $2.90 less than the bead.
The bead costs $1.20 less than the sticker.
What is the cost of 9 stickers more than 5 marbles?
Choose the cheapest item to be 1 u.

Cost of the marble = 1 u
Cost of the bead = 1 u + 2.90
Cost of the sticker = 1 u + 2.90 + 1.20 = 1 u + 4.10

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 2.90 + 1 u + 4.10
= 3 u + 7.00

3 u + 7.00 = 26.50
3 u = 26.50 - 7.00
3 u = 19.50

1 u = 19.50 ÷ 3 = 6.50

Cost of 9 stickers more than 5 marbles
= 9 x (1 u + 4.10) - 5 x 1 u
= 9 u + 36.90 - 5 u
= 4 u + 36.90
= 4 x 6.50 + 36.90
= 26.00 + 36.90
= $62.90

Answer(s): $62.90