Yes, this is the conversion formula to Celsius where C=f(x).
- Subtract 32 from 77=45. So this means 45 Fahrenheit degrees above freezing (measured at 32F).
- Celsius degrees are 5 ninths of Fahrenheit degrees because the range of Fahrenheit is 32 to 212 for the freezing and boiling points of pure water=180 degrees Fahrenheit; while 0-100 is the range for Celsius. 100/180=5/9.
- 5/9*45=25C. This is 25 Celsius degrees above freezing
Incidentally, -40C is the same as -40F. This is the only temperature where the numbers are the same.