The formula C = 5 (F - 32) can be used to convert Fahrenheit temperatures F to 9 Celsius temperatures C. For what Fahrenheit temperatures is the Celsius temperature lower than 45 degrees C?

The given formula C=5 (F-32) should properly read C = (5/9) (F-32), or

9C=5 (F-32).

Using the corrected formula, F = (9C/5) + 32, so for C<45,

F< (9*45/5) + 32=113 degrees

Incidentally, these are the temperatures that yeast can survive. Above 45 degrees C, they might die of heat!