Using the forecasting method, find the Total Cost at Completion $(EA{C}_f)$ based on the period $7$ cumulative totals shown below if the BAC$=320.$

$\backslash$table$[[$Task$,\%$Complete,EV$,AC,$PV$,$CV$,$SV$],[$A$,$Finished,$20,30,20,-10,0],[$B$,$Finished,$15,20,15,-5,0],[$C$,90\%,90,120,100,-30,-10],[$D$,$Finished,$35,60,35,-25,0],[E,0\%,0,0,30,0,-30],[$F$,0\%,0,0,0,0,0],[$Cumulative Totals,,$160,230,200,-70,-40]]$