Ans: $b=\dfrac{4a-7}{3}$
$\begin{array}{rcl}
\dfrac{4a +5b -7}{b} & = & 8 \\
4a + 5b – 7 & = & 8b \\
4a – 7 & = & 3b \\
b & = & \dfrac{4a-7}{3} \\
\end{array}$
$\begin{array}{rcl}
\dfrac{4a +5b -7}{b} & = & 8 \\
4a + 5b – 7 & = & 8b \\
4a – 7 & = & 3b \\
b & = & \dfrac{4a-7}{3} \\
\end{array}$
