# How do you simplify (m - 3) / (3 - m) and what are the restrictions?

$\frac{m - 3}{3 - m} = - 1$ provided $m \ne 3$
Since division by zero is undefined, for the denominator of $\frac{m - 3}{3 - m}$ the value of $m \ne 0$.
$\frac{m - 3}{3 - m} = \frac{\left(- 1\right) \left(3 - m\right)}{3 - m} = - 1$