I'm pretty new to the topic of natural deduction using the Fitch method. I found a very helpful site (http://proofs.openlogicproject.org/) in which you can construct your proofs, but I'm having a lot of trouble with the following:
I get as far as the proof for P but I'm not sure how to then use P to further the proof. I've done a lot of scouring on the net but I just cannot figure out how to continue. Any help would be appreciated.