Year
Month	2016	2017	2018	2019
January	1448	1366	1251	1124
February	707	671	689	646
March	699	687	714	665
April	689	709	690
May	758	761	766
June	693	684	707
July	667	649	681
August	1504	1354	1344
September	1044	977	966
October	695	669	721
November	722	683	748
December	1236	1137	1239

I am needing step by step help on this problem:

The following data report total, monthly U.S. book-store sales in millions of dollars from January 2016 to March 2019. (Go to https://www.census.gov/retail/index.html#mrts, find "Monthly Retail Trade Report," then select "Time Series/Trend Charts" to find the data for the total U.S. bookstore sales.)

d. Evaluate a seasonally adjusted trend forecasting model. What is the MAD? (Round your answers to 4 decimal places.)

e. What is the average monthly trend in book-store sales? (Negative amounts should be indicated by a minus sign. Round your answer to 4 decimal places.)

f-1. What are the monthly indexes?

f-2. When are book sales the highest?

f-3. When are book sales the lowest?

g. Predict book sales for the next 9 months.