Explanation

The formulas for converting between degree Celsius and degree Fahrenheit are: °F = (°C * 9/5) + 32 °C = (°F – 32) * 5/9 To find the temperature when both are equal, we use an old algebra trick and just set ºF = ºC and solve one of the equations. °C = (°C * 9/5) + 32 °C – (°C * 9/5) = 32 -4/5 * °C = 32 °C = -32 * 5/4 °C = -40 °F = (°F * 9/5) + 32 °F – (°F * 9/5) = 32 -4/5 * °F = 32 °F = -32 * 5/4 °F = -40 So the temperature when both the Celsius and Fahrenheit scales are the same is -40 degrees.