Sara's Systems manufactures audio systems for cars. Two models are produced: The Standard model has a budgeted price of $240 and a standard variable cost of $120 The Blaster model has a budgeted price of $520 and a standard variable cost of $200. At the beginning of the year, Sara estimated that she would sell 6,160 Blaster models and 24,640 Standard models. The actual results for the year showed that 7,240 Blaster models were sold for total revenues of $3,040,800. A total of 25,100 Standard models were sold for revenues of $6,275,000. Required: a. Compute the activity variance for the year. (Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, or "U" for unfavorable. If there is no effect, do not select either option.) b. Compute the mix and quantity variances for the year. (Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, or "U" for unfavorable. If there is no effect, do not select either option.) Mix variance Quantity variance