I am currently in the process of studying for the FE (Electrical and Comp) Exam.

Trying to learn some concepts I missed in school and was hoping for some advice with the following question:

The Solution is as follows:

So far I've done little more than copy the problem. I'm just not sure where to go from there, if someone could help me understand the solution, I'd be grateful. Thanks and Best Regards.

- Al -