I'm doing some problems for physics at the end of one the chapters and I get to a question that asks "At what temperature does Fahrenheit and Celsius have the same numerical value?" Now the answer is -40, but I'm not sure how this answer was established. Between class, lab and study time, I've been pouring over physics for the last 7 hours and I'm toasted. I have a feeling that the answer is pretty simple, but I can't seem to get it. Does anybody have any answers?