3 A local council is responsible for gritting roads.
The diagram shows the length, in miles, of the roads that have to be gritted.
\includegraphics[max width=\textwidth, alt={}, center]{76bccb26-f2ec-4798-bb6b-89c922f9651a-03_671_686_488_669}
Total length \(= 87\) miles
The gritter is based at \(A\), and must travel along all the roads, at least once, before returning to \(A\).
- Explain why it is not possible to start from \(A\) and, by travelling along each road only once, return to \(A\).
- Find an optimal 'Chinese postman' route around the network, starting and finishing at \(A\). State the length of your route.