Thermo question

Per unit mass (ie specific) quantities can be converted to rate quantities in open systems by multiplying them by the _______.
I've looked through my book a few times and couldn't find the answer, any help is appreciated.

Up

I can guess that the rate unit to mulitiply by would be from mass per time.  That way, the mass unit would cancel out, and you'd have quantity (moles or whatever) per time unit.  Is that the sort of rates that you've been dealing with?  Per time?