Let's see:
![\frac{5}{9}.(f - 32) = c](https://tex.z-dn.net/?f=%5Cfrac%7B5%7D%7B9%7D.%28f%20-%2032%29%20%3D%20c)
9 is the denominator, if we pass it to the other side it will be as multiplication.
![5.(f - 32) = 9c](https://tex.z-dn.net/?f=5.%28f%20-%2032%29%20%3D%209c)
Now, if we pass 5, the numerador, it will go as denominator.
![f - 32 = \frac{9}{5}.c](https://tex.z-dn.net/?f=f%20-%2032%20%3D%20%5Cfrac%7B9%7D%7B5%7D.c)
Now just add 32 in both sides
![f - 32 + 32 = \frac{9}{5}.c + 32](https://tex.z-dn.net/?f=f%20-%2032%20%2B%2032%20%3D%20%5Cfrac%7B9%7D%7B5%7D.c%20%2B%2032)
![f = \frac{9}{5}.c + 32](https://tex.z-dn.net/?f=f%20%3D%20%5Cfrac%7B9%7D%7B5%7D.c%20%2B%2032)
Ok, this is the formula to discover the temperature in fahrenheit, now let's see the procedures:
A - Multiply both sides of the equation by 9/5, ok
Ad 32 to both sides of the equation, ok
B - Multiply 50 by 9, ok
Divide the answer by 5, ok
Add 32, ok
So both procedures will give the correct temperature.