88p-80p+2=_13

You have an underline in your problem; did you mean a minus sign?

88p - 80p + 2  =  -13                    Combine the 88p with the -80p:

          8p + 2  =  -13                    Subtract 2 from both sides:

                 8p  =  -15                   Divide both sides by 8:

                  p  =  =15/8