Acme Companys production budget for August is 18,900 units and includes the following component unit costs: direct materials, $7.20; direct labor, $11.40; variable overhead, $5.40. Budgeted fixed overhead is $46,000. Actual production in August was 21,840 units, actual unit component costs incurred during August include direct materials, $9.60; direct labor, $10.80; variable overhead, $6.20. Actual fixed overhead was $48,900, the standard direct labor cost per unit consists of 0.5 hour of labor time at $22.8 per hour. During August, $235,872 of actual labor cost was incurred for 9,360 direct labor hours. Required: Calculate the labor rate variance and labor efficiency variance for August. (Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable.)