Acme Company's production budget for August is 18,100 units and includes the following component unit costs: direct materials, $8.0; direct labor, $10.5; variable overhead, $6.5. Budgeted fixed overhead is $38,000. Actual production in August was 19,872 units. Actual unit component costs incurred during August include direct materials, $9.00; direct labor, $10.00; variable overhead, $7.50. Actual fixed overhead was $40,100. The standard variable overhead rate per unit consists of $6.5 per machine hour and each unit is allowed a standard of 1 hour of machine time. During August, $149,040 of actual variable overhead cost was incurred for 21,600 machine hours. Required: Calculate the variable overhead spending variance and the variable overhead efficiency variance. (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).) Variable overhead spending variance Variable overhead efficiency variance