Multiply the numerator and denominator by 6x (the common denominator of 2, 3 and x):
(6-3x)/(2x-x^2)=3(2-x)/(x(2-x)).
The common factor 2-x cancels out (unless x=2) and we're left with 3/x.
[Let's look at the detail of multiplying each term by 6x:
6x*1/x=6; 6x*1/2=3x; 6x*1/3=2x; 6x*x/6=x^2.]