(PB6) Corolla Manufacturing has a standard cost for steel of $20 per pound for a product that uses 4 pounds of steel. During September, Corolla purchased and used 4,200 pounds of steel to make 1,040 units. They paid $20.75 per pound for the steel. Compute the following for the month of September: a) the direct materials price variance, b) the direct materials quantity variance, and c) the total direct materials cost variance