Need some help with these, I get them all wrong, i would love the ancwers and an explination, thnaks

Rodarta Corporation applies manufacturing overhead to products on the basis of standard machine-hours. The company's predetermined overhead rate for fixed manufacturing overhead is $1.20 per machine-hour and the denominator level of activity is 6,600 machine-hours. In the most recent month, the total actual fixed manufacturing overhead was $8,340 and the company actually worked 6,400 machine-hours during the month. The standard hours allowed for the actual output of the month totaled 6,480 machine-hours. What was the overall fixed manufacturing overhead volume variance for the month? Multiple Choice $240 Favorable $144 Unfavorable $240 Unfavorable $96 Favorable