Question

p - 4 = -9 + p. Please help.

Answer 1

Easy, take:

p-4=-9+p

Isolate the variable, this is what you are trying to find (p)

p-4=-9+p
-p        -p

-4=-9.

There is no variable, which means, there is NO SOLUTION!

You can put no solution, or ∅, as an answer.