Ruby Company produces a chair for which the standard specifies 7 yards of material per unit. The standard price of one yard of material is $10.00. During the month, 7,200 chairs were manufactured, using 49,900 yards at a cost of $9.40 per yard. Determine the following: Enter favorable variances as negative numbers. a. Direct materials price variance b. Direct materials quantity variance $ c. Total direct materials cost variance