Japan Company produces lamps that require 3 standard hours per unit at an hourly rate of $17.90 per hour. Production of 7,400 units required 21,760 hours at an hourly rate of $18.40 per hour. Enter favorable variances as negative numbers. (a) Determine the direct labor rate variance. $ (b) Determine the direct labor time variance. $ (c) Determine the cost variance. $