Find Equations of the Tangent Lines to the Curve $y = \frac { x - 10 } { x + 10 }$

Multiple Choice

Find equations of the tangent lines to the curve $y = \frac { x - 10 } { x + 10 }$ that are parallel to the line $x - y = 10$ .

A) $x - y = - 4.5$
B) $x - y = - 2$
C) $x - y = - 12.5$
D) $x - y = - 19.75$
E) $x - y = - 15$