Question

We could have made a better job of it than we did. (Begin with :We did not do)

Answer 1

We did not make the best of it. (I Guess)

Answer 2

Although the given sentence ‘we could have made a better job of it than we did’ is already correct grammatically; however if you want to begin it with ‘we did not do’ then the most appropriate form of the sentence will be as follows:

We did not do well; we could have made a better job of it.