Find the equation of the tangent line to the curve at the given point...

Find the equation of the tangent line to the curve at the given point: y = (x - 1) / (x - 2) , coordinates (3, 2).

I'm trying so hard to figure out the derivative of the function, but I just can't do it...

y'= -1/(x-2)² =m slope
point (3,2)
x=3, m= -1/1=-1

y-2= -1(x-3)
y= -x +3 +2
y= -x +5