please help

a. Use the simple exponential smoothing with a=0.2 for making forecasts. Note: Do not round intermediate calculations. Round final answers to 2 decimal places. b. Use the in-sample forecast errors to compute MSE,MAD, and MAPE. Note: Do not round intermediate calculations. Round final answers to 2 decimal places. c. Make a forecast for period 21. Note: Do not round intermediate calculations. Round final answer to 2 decimal places. \begin{tabular}{|l|l|l|} \hline 1 & t & yt \\ \hline 2 & 1 & 77 \\ \hline 3 & 2 & 86 \\ \hline 4 & 3 & 82 \\ \hline 5 & 4 & 82 \\ \hline 6 & 5 & 74 \\ \hline 7 & 6 & 79 \\ \hline 8 & 7 & 81 \\ \hline 9 & 8 & 77 \\ \hline 10 & 9 & 77 \\ \hline 11 & 10 & 76 \\ \hline 12 & 11 & 85 \\ \hline 13 & 12 & 84 \\ \hline 14 & 13 & 86 \\ \hline 15 & 14 & 95 \\ \hline 16 & 15 & 85 \\ \hline 17 & 16 & 93 \\ \hline 18 & 17 & 95 \\ \hline 19 & 18 & 93 \\ \hline 20 & 19 & 92 \\ \hline 21 & 20 & 86 \\ \hline \end{tabular}