Find the Indicated Limit If It Exists $$\lim _ { x \rightarrow 6 } \frac { x - 6 } { x ^ { 2 } - 36 }$$

Find the indicated limit if it exists. $$\lim _ { x \rightarrow 6 } \frac { x - 6 } { x ^ { 2 } - 36 }$$