An unsupervised k$-$means clustering produces $4$ clusters. The size of each cluster is as follows:

Cluster $1=73$ instances

Cluster $2=109$ instances

Cluster $3=82$ instances

Cluster $4=45$ instances

When calculating the silhouette coefficient for a single data instance in Cluster $3,$ to compute bi $($separation$),$ how many distance calculations must be performed? How many distance calculations are required to compute ai $($cohesion$)$ for that data instance in Cluster $3?$ Be sure to show your work for these calculations.