Assume that Vernon actually produced and sold 21,000 books. The actual sales price and costs incurred follow: Required a. \& b. Determine the flexible budget variances and also Indicate whether each variance is favorable (F) or unfavorable (U). (Select "None" if there is no effect (i.e., zero variance).) a. \& b. Determine the flexible budget variances and also Indicate whether each variance is favorable (F) or unfavorable (U). (Select "None" if there is no effect (i.e., zero variance).)