Time calculated in Hours and Minutes

Is there a way to subtract two time fields (for an elapsed time) and have the results be in an "Hours and Minutes" format? When I subtract Start Time from End Time (and divide by 3600) I get a proper number of hours, but the minutes portion of the answer is a fraction of an hour instead of a number of minutes. Instead of a result of "2.75" (indicating 2 and three-quarters of an hour) I would like it to be "2:45" (indicating two hours and forty-five minutes).