5 x − 36x + 36 = 0 help me learn how to solve this

If you mean

5x − 36x + 36 = 0
then proceed as in
-31x + 36 = 0
-31x = -36
x = 36/31

But if you meant
5x^2 − 36x + 36 = 0 then you have to factor it somehow, or use the quadratic formula. Factoring, you get
(5x-6)(x-6) = 0
x = 6/5 or 6