Adam pays $24.90 for a marble, a bead and a sticker.
The marble costs $3.90 less than the bead.
The bead costs $1.50 less than the sticker.
What is the cost of 8 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 + 3.90
Cost of the sticker = 1 u + 3.90 + 1.50 = 1 u + 5.40

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 3.90 + 1 u + 5.40
= 3 u + 9.30

3 u + 9.30 = 24.90
3 u = 24.90 - 9.30
3 u = 15.60

1 u = 15.60 ÷ 3 = 5.20

Cost of 8 stickers more than 5 marbles
= 8 x (1 u + 5.40) - 5 x 1 u
= 8 u + 43.20 - 5 u
= 3 u + 43.20
= 3 x 5.20 + 43.20
= 15.60 + 43.20
= $58.80

Answer(s): $58.80