Total variable overhead variance

The standard cost of the variable overheads is (17,600 + 6,000 + 4,400) / 8,000 = $3.50 per hour. The actual total variable overheads are $30,580. The standard cost for the actual hours worked is 8,400 x 3.50 = $29,400. Therefore the variance is 30,580 - 29,400 = $1,180 adverse. Again, I suggest that you watch my free lectures rather than try and learn equations.

Sir but I didn't just use equations These equations are there in the study text In the study text it says that to find the total variable overhead variance we have to add the expenditure variance and efficiency variance So I used the expenditure variance equation which is actual rate multiplied by actual hours substracted by actual hours into standard rate And then there was this other efficiency variance equation that was actual hours minus standard rate substracted by standard hours into standard rate My doubt now is in regard with why these study text equations do not usually work on questions such as these Around most of the time these textbook equations work but sometimes it doesn't like in the case of this question But nontheless I will watch your lectures also to make sure i understand the topic because even I feel like I'm weak in this topic

The total variance is indeed the expenditure variance plus the efficiency variance. However your Study Text should present it the other way round. The expenditure and efficiency variance are the way of analysing the reason for the total variance. The reason your approach did not work is that you were treating it as though we were dealing with units (which normally is the case, but is not the case here). If the question had told the actual and standard hours per unit, then you would have an efficiency variance, but that is not the case here. The only variance is the expenditure variance. When (as is usual) you are given details about the units, then you can certainly be asked in the exam to calculate the expenditure and/or the efficiency variance, but if all you are asked for is the total variance it will waste too much time to do it the way that you were trying to do it. One of the biggest problems in the exam is the time pressure.