Find the Exact Value of the Expression $$\frac { \tan 70 ^ { \circ } - \tan \left( - 50 ^ { \circ } \right) } { 1 + \tan 70 ^ { \circ } \tan \left( - 50 ^ { \circ } \right) }$$

Multiple Choice

Find the exact value of the expression.
- $$\frac { \tan 70 ^ { \circ } - \tan \left( - 50 ^ { \circ } \right) } { 1 + \tan 70 ^ { \circ } \tan \left( - 50 ^ { \circ } \right) }$$

A) $- 2$
B) $- \frac { \sqrt { 3 } } { 3 }$
C) $- \frac { 1 } { 2 }$
D) $- \sqrt { 3 }$