please explain every step for a and b

Question 1) Demand observations for a specific part stocked at a parts supply warehouse during the 2016 calendar year; Demand Month Month January February March April May June 89 57 144 221 177 280 July August September October November December Demand 223 286 212 275 188 3121 a) Determine the one-step-ahead forecasts for the demand for January 2017 using 3-, 6- , and 8-month moving averages. Compute the one-step-ahead three-month and six- month moving-average forecasts for July through December. Explain what effect does increasing N from 3 to 6 have on the forecasts. b) Using a four-month moving average, determine the one-step-ahead and two-step- ahead forecast for July through December 2016. (Hint: The two-step-ahead forecast for July is based on the observed demands in February through May.) and compute MAD for the forecasts. Which method gave better results