\[\frac{5b + 1}{b + 2} - 4^{\backslash b + 2} =\]
\[= \frac{5b + 1 - 4 \cdot (b + 2)}{b + 2} =\]
\[= \frac{5b + 1 - 4b - 8}{b + 2} = \frac{b - 7}{b + 2}\]