Multiple choice At what temperature are Celsius and Fahrenheit equal? What? Not at any temperature! 13°C and 13°F -40 °C and -40 °F. 20°C and 20°F Reveal answer Fill a bubble to check yourself C Correct answer Explanation The formula to convert Celsius to Fahrenheit is F = (C * 9/5) + 32. Setting F = C and solving gives -40 = -40.