I have a very hard time with variances. can someone help me with this please?

Fixed Overhead Variances Assume that ExxonMobil uses a standard cost system for each of its refineries. For the Houston refinery, the monthly fixed overhead budget is 58,800,000 for a planned outputs of 5,000,000 barrels. For September, the actual fixed cost we $9,450,000 for 5,100,000 barrels. a. Determine the fixed overhead budget variance. b. If fixed overhead is applied on a per-barrel basis, determine the volume variance