Find All Values of X Satisfying the Given Conditions $y _ { 1 } = \frac { 1 } { x + 5 } , y _ { 2 } = \frac { 3 } { x + 4 } , y _ { 3 } = \frac { - 1 } { x ^ { 2 } + 9 x + 20 }$

Multiple Choice

Find all values of x satisfying the given conditions.
- $y _ { 1 } = \frac { 1 } { x + 5 } , y _ { 2 } = \frac { 3 } { x + 4 } , y _ { 3 } = \frac { - 1 } { x ^ { 2 } + 9 x + 20 }$ , and $y _ { 1 } + y _ { 2 } = y _ { 3 }$

A) $\{ 4 \}$
B) $\{ 0 \}$
C) $\{ - 5 \}$
D) $\varnothing$