Yes, at -40, both Celsius and Fahrenheit are equal, as shown below:
Use the formula for conversion from Celsius and Fahrenheit, i.e., T(°C) = (T(°F) - 32)/9 × 5.
Substitute x in the above equation for both temperature scales, x(°C) = (x (°F) - 32)/9 × 5.
Solve for x, and you will get x = -40.
Hence both Celsius and Fahrenheit are equal at -40 °C and -40 °F.
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