Tavorn Corporation applies manufacturing overhead to products on the basis of standard machine-hours. The company's standard variable manufacturing overhead rate is $1.80 per machine-hour. The actual variable manufacturing overhead cost for the month was $13,080. The original budget for the month was based on 7,100 machine-hours. The company actually worked 7,210 machine-hours during the month. The standard hours allowed for the actual output of the month totaled 7,070 machine-hours. What was the variable overhead efficiency variance for the month? A. $354 unfavorable B. $252 unfavorable C. $54 favorable D. $102 unfavorable Please show me the work not just the answer, Thanks so much