please explain a and b parts step by step properly. use excel for this question.

The GNP for each quarter of the past 4 years is shown in the following table: (a) Forecast the GNP for the first quarter of year 5 by using exponential smoothing model with a=1. Assume that the forecast for the first quarter of year 1 is equal to the actual value. (b) What is the linear trend equation that best fits the data? Forecast the GNP for the first quarter of year 5 by using this equation. (use Excel to answer this part) Year 1 2 2 Quarter 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 GNP (Billions) $ 9027 $ 9092 $ 9194 $ 9367 $ 9505 $ 9588 $ 9726 $ 9938 $ 10063 $ 10238 $ 10285 $ 10375 $ 10430 $ 10473 $ 10501 $ 10580 3 4