temperature: swap formulae for Fahrenheit and Celcius

They were the wrong way around

Author: thepabloaguilar

exercises/concept/temperature/.docs/hints.md

@@ -2,12 +2,12 @@
 
 ## Convert Farenheit to Celsius
 
-- Temperature in degrees Celsius is defined as: T(°F) = T(°C) × 1.8 + 32
+- Temperature in degrees Celsius is defined as: T(°C) = (T(°F) - 32) / 1.8
 - The temperature in Farenheit is provided as an `Integer` and must return Celsius as a `Float`.
   The `fromInteger` function will come in handy.
 
 ## Convert Celsius to Farenheit
 
-- Temperature in degrees Fahrenheit is defined as: T(°C) = (T(°F) - 32) / 1.8
+- Temperature in degrees Fahrenheit is defined as: T(°F) = T(°C) × 1.8 + 32
 - The temperature in Celcius is provided as a `Float` and must return Farenheit rounded up to the closest `Integer`.
   The `ceiling` function will come in handy.