We agreed last time that it doesn't matter whether he gets it right, if that is even possible, he's likely screwed anyway. Because>Option 1
He gets it right in accordance with what Grover had decided to be correct. Grover gets annoyed that he's been bested and kills Johnson without comment.>Option 2
Johnson gets it wrong according to Grover's solution, and gets the bullet after Grover gloats and explains how stupid Johnson is for thinking THAT was the answer
Johnson gets it objectively right. Grover, being the psycho he is, arrived at an objectively wrong answer, but since he's the one calling the literal shots, everything proceeds according to option 2.
tl;dr it's an altogether fucked up situation with little to no chance of survival.