Question

Is it wise for a firm to employ a worker at $20 per hour when another worker doesn't same job for $10 per hour

Answer 1

So, the company has a  choice: it can presumably employ one worker or the other, and they seem to do the job equally well ( I think that the "doesn't" was a typo and you actually meant "does" - it fits better into the sentence structure). The only difference seems to be the prize.

then it's not wise to employ the more expensive employee!