Given the following information, draw the precedence diagram. How many following tasks does Task B have? $($slides $25-28)$

$\backslash$table$[[$Task$,$Time$($sec$),$Predecessor$($s$)],[$A$,30,$none$],[$B$,20,$A$,$ C$],[$C$,10,$none$],[$D$,40,$B$],[$E$,30,$B$],[$F$,20,$E$],[$G$,40,F$