\[\frac{7}{b + 2} - \frac{5b}{b - 5}\]
\[\ b + 2 \neq 0\]
\[\ b - 5 \neq 0 \Longrightarrow b \neq - 2,\ b \neq 5.\]
\[при\ b - любое\ число,\ \]
\[кроме\ x = - 2;b = 5.\]