What Is The Temperature In Fahrenheit Exactly Three Times That In Celsius?

C = 5/9(F-32)  is the conversion from Fahrenheit to Celsius.
We want
  F = 3C = 3(5/9)(F-32)    (substitute for C)
  F = 5/3(F-32)    (reduce the fraction)
  3F = 5(F - 32)    (multiply by 3)
  3F = 5F - 160    (use the distributive property)
  0 = 2F - 160    (subtract 3F)
  160 = 2F    (add 160)
  80 = F    (divide by 2)
  C = 5/9(80 - 32) = 5/9*48 = 240/9 = 26 2/3

The temperature of 80 ºF is exactly 3 times numerical value of the corresponding 26 2/3 ºC.