$[10]$ Determine the minimum cost increase to reduce the project duration by $3$ days.

$\backslash$table$[[$Activity$,\backslash$table$[[$Preceded$],[$by$]],\backslash$table$[[$Nominal$],[$Duration$]],\backslash$table$[[$Nominal$],[$Cost$]],\backslash$table$[[$Crash$],[$Duration$]],\backslash$table$[[$Crash$],[$Cost$]]],[$A$,--,4,250,2,550],[$B$,--,3,200,1,600],[$C$,--,8,750,6,1,350],[$D$,$A$,6,500,3,650],[$E$,$A$,$B$,9,1,300,8,1,900],[$F$,$D$,$E$,2,800,1,1,800],[$G$,$C$,3,400,2,450]]$

ANSWER: $$1,100$; crash A by $1$ day $(+$$$150),$ then AB by one day $(+350)$ then $E$ by $1$ day $(+600)$