Forecasting Method: Weighted Moving Average with $N=3.$ Using this method, please forecast weekly auto sales from week $6$ to $8.$

$\backslash$table$[[$Week$,$Demand $($D$),$Average $($A$),$Forecast $($F$)],[1,100,,-],[2,150,,-],[3,130,A_3=0\mathrm{.}5**130+0\mathrm{.}3**150+0\mathrm{.}2**100=130,-],[4,140,A_4=0\mathrm{.}5**140+0\mathrm{.}3**130+0\mathrm{.}2**150=139,F_4=130$