please include work, i would like to understand. thank you!

Edwards and Bell market a single line of home computers, dubbed the XL-98. The master budget for the coming year contained the following items: sales revenue, $402,000 variable costs, $251,000, fixed costs, $100,200. Actual results for the year were as follows: sales revenue, $351,000; variable costs, $225,200; fixed costs, $95,400. The flexible-budget operating income for the year was $35,200. a. What is the total master (static) budget variance in operating profit for the period? b. What portion of the total master (static) budget variance is attributable to actual sales volume being different from planned sales volume? c. What portion of the total variance is due to a combination of selling price and costs (variable cost per unit and total fixed costs) being different from budgeted amounts? a. Total master (static) budget variance b. Sales volume variance c. Flexible-budget variance