If you drink two beers over 2and a half hours and have to take a urine test 3 and a half hours later will it show up

That's a question for an advanced bio-chem class. There is really no way of calculating EtOH elimination in that close of a time frame without specific knowledge of the rate of consumption, your metabolism and several other factors. Would also need to know the testing level of the method used.

There may be a short-cut however. When was the last time you urinated prior to the test?