I am signed up for a triathlon in June 2016, It goes from 9 AM-9 PM, we must run 30 miles, bike 60 miles, and swim 3. I believe I am fit for it because I can bike 15 mph forever on, but I swam a half mile in 20 minutes, and I can run for 2.5 miles easily. I am biking 10 miles a day, swimming 1, and running 2 miles total. This is combined with weights and calisthenics. Is this enough?
As it stands, you may be fit enough, but you are not trained enough, unless you plan on walking pretty much the entire run portion of the event.
Most marathon plans (Which is a distance shorter than the 30 miles) will have you running 50-70 miles a week, with quite a few runs in the 10-15 mile range.
However, I think the biggest limiter right now is your swimming. At 20 minutes per 1/2 mile, you are going to be in the water for two hours, assuming you can hold the same pace the entire time. That is a very long time to be in the water doing full body exercise.
What I would recommend is set up your own "mini" triathlon. Drive your bike to a local lake or pool. Swim your 1/2 mile, get on the bike and ride 30-40 miles at your 15 mph pace (Out and back, then throw your bike into the car), and then go run 2-3 miles. It's a lot more difficult than you think, when you stack everything on top of each other.
If you maintain the same level of training you have now, I would predict that you would end up not finishing the bike leg, or possibly finishing it outside of the time cutoffs (Most 1/2 Iron distance events, which is about what that is have time limits for each event).
My recommendation would be to go to a site such as beginnertriathlete.com, and look at their 1/2 Ironman plans. I would also confirm the distances, as the one that you describe has a run leg that is more than a full Ironman run distance, and a swim leg that is 50% longer than an Ironman distance. (Are you sure it wasn't 3k, 60k, 30k? That would make it about 1.5 mile swim, 37 mile bike and 18 mile run. Still odd distances, but much closer than if it is miles).
The biking in that triathlon seems to be really short compared to the running and the swimming. But running that distance require stepping a the distance gradually. So I would recommend that you try to step up the running distance slowly and see how it feels, that is probably one of the best ways to see if you are fit also. The other legs doesn't sound that bad.
Also, try do some running after the biking and get to know that feeling.