Please help me with this problem and incluse step by step instructions. No excel Sales of tablet computers at Marika Gonzalez's electronics store in Washington, D$.$C$.,$ over the past $10$ weeks are shown in the table below:

a$)$ The forecast for weeks $2$ through $10$ using exponential smoothing with $=0\mathrm{.}55$ and a week $1$ initial forecast of $21\mathrm{.}0$ are $($round your responses to two decimal places$)$:

b$)$ For the forecast developed using exponential smoothing $(=0\mathrm{.}55$ and initial forecast $21\mathrm{.}0),$ the MAD $=$ sales $($round your response to two decimal places$).$

c$)$ For the forecast developed using exponential smoothing $(=0\mathrm{.}55$ and initial forecast $21\mathrm{.}0),$ the tracking signal $=|,($round your response to two decimal places$).$