Grace Company manufactures tables with glass tops. The standard material cost for the glass used per Style-R table is P7.80 based on 6 square feet of vinyl at a cost of P1.30 per square foot. A production run of 1,000 tables in January resulted in usage of 6,400 square feet of vinyl at a cost of P1.20 per square foot, a total cost of P7,680. The usage variance resulting from the above production run was: 0 480 unfavorable O 640 favorable 120 favorable O 520 unfavorable