please help i want to learn how to do this by hand NO EXCEL

3. A cooking oil distributor distributes oil to major supermarkets in the region. Though a person's daily consumption of oil seems to be almost the same, the distributor's demand for oil fluctuates every month. The distributor consolidates the order from all supermarkets and initiates his ordering and delivery processes. An accurate forecast is essential to reduce the variability of demand and supply of oil supply chain. The following table provides the distributor's overall sales made during the last 10 months (sales in gallons of oil). Month Sales 1 12,137 2 14,729 3 15,146 4 16,559 5 18,992 6 21,192 24,560 8 26,883 9 28,926 10 32,592 a. Compute an exponentially smoothed forecast, using an a value of 0.35. b. Compute an adjusted exponentially smoothed forecast (with a=0.35 and 3-0.40). c. Compare the two forecasts using MAD and indicate which seems to be more accurate. Based on the accurate method, what is the forecast for the 11th month