The domain is the range of x values which give f(x) a value that is unique, such there is only one y value per x value.
Here, since the x is on the bottom of the fraction, it cannot have any value such that the whole denominator equals zero, i.e. d(x)!=0 d(x)=text(denominator of the fraction that is a function of) x.
x-2!=0
x!=2
Now, the range is the set of y values given for when f(x) is defined. To find any y values that cannot be reached, i.e. holes, asymptotes, etc. We rearrange to make x the subject.
y=5/(x-2)
x=5/y+2, y!=0 since this would be undefined, and so there are no values of x where f(x)=0. Therefore the range is f(x)!=0.