If I understand your question well, I suppose you mean [tex] \frac{4}{ x^{2} -35} - \frac{1}{x+5} [/tex]
[tex]\frac{4}{ x^{2} -35} - \frac{1}{x+5} = \frac{4}{(x+5)(x-7)}- \frac{1}{x+5} \\ = \frac{1}{x+5}( \frac{4}{x-7}-1) \\ = \frac{1}{x+5}( \frac{4}{x-7}- \frac{x-7}{x-7}) \\ = \frac{1}{x+5}( \frac{4-x+7}{x-7}) \\ = \frac{1}{x+5}( \frac{11-x}{x-7}) \\ = \frac{11-x}{ x^{2} -35} [/tex]
