Acme Company's production budget for August is 17,600 units and includes the following component unit costs: direct materials, $7.7; direct labor, $10.1; variable overhead, $6.2. Budgeted fixed overhead is $33,000. Actual production in August was 18,810 units. Actual unit component costs incurred during August include direct materials, $8.50; direct labor, \$9.10; variable overhead, \$6.90. Actual fixed overhead was $34,600. The standard variable overhead rate per unit consists of $6.2 per machine hour and each unit is allowed a standard of 1 hour of machine time. During August, \$129,789 of actual variable overhead cost was incurred for 19,665 machine hours. Required: Calculate the variable overhead spending variance and the variable overhead efficiency variance. Note: Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance)