Assume that Gibson 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 the effect of each variance by selecting favorable (F) or unfavorable (U). Note: Select "None" if there is no effect (i.e., zero variance). \begin{tabular}{||l|l|} \hline Contribution margin & \\ \hline Fixed costs & \\ \hline Manufacturing overhead & \\ \hline Selling, general, and administrative costs & \\ \hline Net income & \\ \hline \end{tabular} Assume that Gibson 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 the effect of each variance by selecting favorable (F) or unfavorable (U). Note: Select "None" if there is no effect (i.e., zero variance). \begin{tabular}{||l|l|} \hline Contribution margin & \\ \hline Fixed costs & \\ \hline Manufacturing overhead & \\ \hline Selling, general, and administrative costs & \\ \hline Net income & \\ \hline \end{tabular}