$.$ Repeat the process you just stepped through to identify the smallest subtour from LP$3($it should be similar to the one you just eliminated, but with $4$ cities included instead of $3).$ Add a constraint to eliminate this subtour $($since it has $4$ cities, your constraint should require that the sum of the $4$ arcs in the subtour must be $<=3).$ List the arcs in this subtour. After adding the new constraint, solve the resulting LP $($LP$4)$ and record its objective function value.