if you notice on mine I let (-3+p) equal 5 and -5, because definition of modulus says answer is positive or negative. Squaring both sides is also fine...you should get quadratic equation p^2 -6p-16=0 , when you solve you also get p=8 and p=-2. Hope this clarifies.
sorry its a typo from me. But answer is correct. it should read -64+88+56=80 (Apologies when you do -22(-4) you get 88 but I wrote 80 by mistake). Hope this clarifies