Russell and Sons, a CPA firm, established the following standard labor cost data for completing what the firm referred to as a Class $2$ tax return. Russell expected each Class $2$ return to require $3\mathrm{.}9$ hours of labor at a cost of $$45$ per hour. The firm actually completed $710$ Class $2$ returns. Actual labor hours averaged $3\mathrm{.}5$ hours per return and actual labor cost amounted to $$52$ per hour.