forecasting theory

the six manth sales daba is shown on teble a) get first difference of the data series DbDt1 b) Use daniel test to Shom the test difference series(trend (q=0.05)) C) Find one step forecast value of the first differnce sevies d) use the forecast you find in (C) to find D. the six manth sales daba is shown on teble a) get first difference of the data series DbDt1 b) Use daniel test to Shom the test difference series(trend (q=0.05)) C) Find one step forecast value of the first differnce sevies d) use the forecast you find in (C) to find D