Excercise 3, chapter 9

[jcornickm]

Am I missing something (chances are I am) or is Excersice 9.3.3 well beyond the scope of this book? Here is an example of a proof that p values are uniformly distributed under the null:

https://statproofbook.github.io/P/pval-h0.html

If there is an easier way, can you point me in its direction?