Answer
$=3, \quad x\neq 2$
Work Step by Step
The fractions have a common denominator, we subtract the numerators...
$\displaystyle \frac{4x-10}{x-2}-\frac{x-4}{x-2}=\frac{4x-10-(x-4)}{x-2}$
$=\displaystyle \frac{3x-6}{x-2}$
... factor what we can...
$=\displaystyle \frac{3(x-2)}{(x-2)}$
... exclude values that yield 0 in the denominator:
$x\neq 2$
... and, cancel the common factor
$=3, \quad x\neq 2$
