What's the easiest way to calculate remaining hours at project level?

[Jyo_Mohanraj]

I have 2 fields one is Planned Hours and another is completed hours and I'm using this calculation which isnt working

displayname=Remaining Hours

linkedname=direct

namekey=totalHours

textmode=true

valueexpression=SUB(work,completedHours)

valueformat=doubleAsInt