I'm not able to understand how they got from probability U is less than e to the power of x to e^-x? shouldn't it be e^x instead because we are given in our notes that probability U that's less than u is = u so probability u is less than e to the power of x should be should be = e^x and not e^-x? Also, for the line after that how did they get e^mod x? What exactly are we considering when we consider the case when x<0 and when x>0.
Any help would be much appreciated.