Table $7\mathrm{.}5$ contains information about an environmental cleanup project in the township of Hiles. Shorten the project three weeks by finding the minimum$-$cost schedule. Assume that project indirect costs and penalty costs are negligible. Identify activities to crash while minimizing the additional crash costs.

TABLE $7\mathrm{.}5||$ ENVIRONMENTAL PROJECT DATA

$\backslash$table$[[$Activity$,\backslash$table$[[$Normal$],[$Time$],[($weeks$)]],\backslash$table$[[$Crash$],[$Time$],[($weeks$)]],\backslash$table$[[$Cost to Crash$],[($$ per week$)]],\backslash$table$[[$Immediate$],[$Predecessor$($s$)]]],[$A$,7,6,200,$None$],[$B$,12,9,250,$None$],[$C$,7,6,250,$A$],[$D$,6,5,300,$A$],[$E$,1,1,-,$B$],[$F$,1,1,-,$C$,$ D$],[$G$,3,1,200,$D$,$ E$],[$H$,3,2,350,$F$],[$I$,2,2,-,$G$]]$