A temperature appears the same in both the Fahrenheit and Celsius thermometers. What is its value?

-20°C = -20°F

-40°C = -40°F

-25.6°C = -25.6°F

-51.2°C = -51.2°F

-17.7°C = -17.7°F

-57.6°C = -57.6°F

-64°C = -64°F