Load it onto a reel, pop it into the daylight tank, and in room light see if the now accessible head end of the backing paper has more information on it.

Otherwise look up what conventional 100 speed b&w films (if you are pretty sire it is b&w) take to develop in your developer and dilution of choice.

Don't be afraid to go a bit long; denser negs take longer to print; underdeveloped negs are a worse alternative. If they are difficult to pritn as dense, and are worth the effort, they can be reduced.