Adam pays $27.70 for a marble, a bead and a sticker.
The marble costs $3.60 less than the bead.
The bead costs $1.30 less than the sticker.
What is the cost of 7 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 + 3.60
Cost of the sticker = 1 u + 3.60 + 1.30 = 1 u + 4.90

Total cost of the marble, the bead and the sticker
= 1 u + 1 u + 3.60 + 1 u + 4.90
= 3 u + 8.50

3 u + 8.50 = 27.70
3 u = 27.70 - 8.50
3 u = 19.20

1 u = 19.20 ÷ 3 = 6.40

Cost of 7 stickers more than 5 marbles
= 7 x (1 u + 4.90) - 5 x 1 u
= 7 u + 34.30 - 5 u
= 2 u + 34.30
= 2 x 6.40 + 34.30
= 12.80 + 34.30
= $47.10

Answer(s): $47.10