what is the Mad for periods 5-9? show work

Use the following data to answer the next five questions. Monthly sales for the past nine periods along with the associated forecasts are shown in the following table. Begin to compute the tracking signal starting in period five by updating the MAD with exponential smoothing. Use an alpha value of 0.25 . Remember, you are computing a MAD and tracking signal, not a new forecast. Keep at least two decimal points in all your calculations. More is fine