Tutorial $1$: Productivity: Q$2$

United Tire Service completed $100$ tire changes, six brake jobs, and $16$ alignments in an eight$-$hour day with its standard crew of six mechanics. A brake specialist costs $$16$ per hour, a tire changer costs $$8$ per hour, and an alignment mechanic costs $$14$ per hour. The materials cost for a day was $$2000,$ and the overhead cost was $$500.$

a$)$ Calculate the shop's labor productivity if the retail price for each respective service is $$60,$$$150,$ and $$40.$

b$)$ What is the multifactor productivity, if the crew consisted of two of each type of mechanic?