Patel and Sons Incorporated uses a standard cost system to apply factory overhead costs to units produced. Practical capacity for the plant is defined as 50,000 machine hours per year, which represents 25,000 units of output. Annual budgeted fixed factory overhead costs are $250,000 and the budgeted variable factory overhead cost rate is $4 per unit. Factory overhead costs are applied on the basis of standard machine hours allowed for units produced. Budgeted and actual output for the year was 20,000 units, which took 41,000 machine hours. Actual fixed factory overhead costs for the year amounted to $245,000, while the actual variable overhead cost per unit was $3.90. Based on the information provided above, calculate the following factory overhead variances for the year. Indicate whether each variance is favorable (F) or unfavorable (U). (Do not round intermediate calculations. Round your answers to the nearest whole dollar amount.) (a) Total overhead variance (b) Total flexible-budget variance (c) Production volume variance