Find the Exact Value of the Expression $$\frac { 1 - \tan 80 ^ { \circ } \tan 70 ^ { \circ } } { \tan 80 ^ { \circ } + \tan 70 ^ { \circ } }$$

Multiple Choice

Find the exact value of the expression.
- $$\frac { 1 - \tan 80 ^ { \circ } \tan 70 ^ { \circ } } { \tan 80 ^ { \circ } + \tan 70 ^ { \circ } }$$

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