Answer :
[tex]a(n-3)+8=bn\ \ \ |Omit\ the\ bracket\\\\
an-3a+8=bn\ \ \ |Subtract\ bn\\\\
an-bn-3a+8=0\ \ \ |Add\ 3a\\\\
an-bn+8=3a\ \ \ |Subtract\ 8\\\\
an-bn=3a-8\\\\
n(a-b)=3a-8\ \ \ |Divide\ by\ (a-b)\\\\
\boxed{n=\frac{3a-8}{a-b}}
[/tex]
