I agree with Brian in the sense that CT fourier transforms are pretty straight forward when you set up them up with the integral and simplifying/combining terms, but actually computing them can be difficult to keep straight. For example with number 21, it just got to be confusing when you have to sit down and think of the different ways to solve each problem. Just trying to keep things straight gets complicated and not making a mistake. But i suppose learning all the properties by heart and knowing how to apply them in what situations is the key to this.
