Ruby Company produces a chair for which the standard specifies 6 yards of material per unit. The standard price of one yard of material is $9.60. During the month, 4,800 chairs were manufactured, using 29,100 yards at a cost of $10.08 per yard. Determine the following: Enter favorable variances as negative numbers. . Direct materials price voriance b. Dirct materials quantity variance c. Total direct materials cost variance