Tavorn Corporation applies manufacturing overhead to products on the sources of standard machine-hours. The company's standard variable manufacturing overhead rate is $1.80 per machine-hour. The real 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 really worked 7,210 machine-hours during the month. The standard hours allowed for the definite output of the month totaled 7,070 machine-hours. Evaluate what was the variable overhead efficiency variance for month?