Not sure how to do future predictions

Required information [The following information applies to the questions displayed below.) Alden Co.'s monthly unit sales and total cost data for its operating activities of the past year follow. Management wants to use these data to predict future fixed and variable costs. Month 1 2 3 4 5 6 Units Sold 317,500 162,500 262,500 202,500 287,500 187,500 Total Cost $155,000 98,750 203, 100 97,500 199,000 109,500 Month 7 8 9 10 Units Sold 362,500 267,500 76,500 147,500 91,500 97,500 Total Cost $296,300 149,250 67,500 128, 125 91,500 84,150 11 12 2. Predict future total costs when sales volume is (a) 375,000 units and (b) 415,000 units. Predictions Sales (units) 375,000 415,000 Total