Need explanations in solving partial differential equations

I have 2 study guides with questions an full solutions to Chapters 5, 6, and 12 of my Partial Differential Equations textbook but I am having trouble understanding how certain steps are derived.

I need detailed, dumbed down explanations for all my questions on the study guides which are labeled in red font with a ” Q. ” before it.

Chapter 5 & 6 Study Guide.docx 

Chapter 12.docx 

I would like this to be completed by Wednesday – 8:00 am EST. Thank you.

P.S. I’m very slow when it comes to PDE’s so please explain in really simple terms that a total math illiterate would understand.