Sale percent off %15
discount amount: $6
regular price: x
The shoes are 15% off.
So, if we multiply the original price (x) by that percentage in decimal form (divided by 100) we obtain the discount amount.
Mathematically speaking:
x (15/100) = 6
0.15 x = 6
Solve for x:
x = 6/0.15
x = 40
Regular price: $40