I had one one like that recently. I was able to get it right but after like 5 minutes trying to figure out was happening. It was a mess, I hope I do not get a bunch of those q's on the exam!! Do not worry, do not post it of you feel you do not need to 🙂
Btw I kind of know what is happening now when I see those variances q and I do not think there is a universal formula for them. We have to be able to decipher what they are asking and then know what numbers to use or how to get them. For efficiency or usage variances, Budgeted rate * diferences in budgeted and actual volumes. With Rate variances, Actual volume or quantity * diferences between budgeted rate and actual rate. But they sometimes throw in total fixed OH cost numbers and total OH cost and ask for variable OH rate or volume variance. So in conclusion I do not think there is a universal formula for this nonsense.