Adam pays $24.90 for a marble, a bead and a sticker.
The marble costs $2.20 less than the bead.
The bead costs $1.30 less than the sticker.
What is the cost of 6 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 + 2.20
Cost of the sticker = 1 u + 2.20 + 1.30 = 1 u + 3.50

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 2.20 + 1 u + 3.50
= 3 u + 5.70

3 u + 5.70 = 24.90
3 u = 24.90 - 5.70
3 u = 19.20

1 u = 19.20 ÷ 3 = 6.40

Cost of 6 stickers more than 5 marbles
= 6 x (1 u + 3.50) - 5 x 1 u
= 6 u + 21.00 - 5 u
= 1 u + 21.00
= 1 x 6.40 + 21.00
= 6.40 + 21.00
= $27.40

Answer(s): $27.40