Glendale Valves offers three types of 3 inch valves for sale to retailers: Ball Valves, Butterfly (B.Fly) Valves and Foot Valves. Actual and Budget operating data by product for the most recent reporting period are as follows:

ACTUAL BUDGET Ball B.Fly Foot Ball B.Fly Foot Sales-# valves 45,220 71,400 121,380 57,500 87,500 105,000 Sales Price per valve $449 $190 $125 $450 $200 $120 VC per valve $288 $142 $95 $290 $140 $90

a. Calculate the sales-mix variance for each product and in total.

b. Calculate the sales-quantity variance for each product and in total.

c. Provide an explanation for the primary driver of the sales-mix variance.