I have been disturbed by this complicated problem from www.fofallthings.com and nobody has given me a concrete solution. May be I should not, I don’t know but the problem says: Prove that x ± y = b? Where b is the solution to any given numbers x and y, for which x is P and NP. Is it this possible to prove this? Importantly, this was said to be used as a premise to prove that P = NP. Thanks.