Stadium Construction Project Problem: What is the combined slack for

$\backslash$table$[[$ACTIVITY IMMEDIATE PREDECESSOR DURATION Idavsil,,$],[$A$,$A$,],[$C$,$A$,4],[$D$,$A$,3],[$E$,$B$,6],[$F$,$C$.$D$,],[$G$,$E$,$F$,],[$H$,$D$,],[$I$,4,]]$

$2$

$0$

$1$

$4$

$3$