Please show formula used to answer question.

sThe standard costs and actual costs manufacture of 2568 units of actualroductioa or factory overhead for tn tual production are as follows: _Standard Costs Fixed overhead (based on 10,088 hours) 3 hours $0.78 per hour Variable overhead 3 hours @ $1.90 per hour Actual Costs Total variable cost, $17867 Total fixed cost, $7822 Determine the amount of the factory overhead cost variance. a. $2429 unfavorable b. $3229 unfavorable c. $2429 favorable d. $5659 unfavorable