The hint, d = r*t, is a really helpful one. Here, distance is 220 miles and time is 5 hours, 30 minutes. Rate is the unknown that we are solving for.
You would set up the problem as follows:
220 = r * 5.5
(I've converted the time to hours, since hours and minutes are different units.) You would solve this problem by dividing both sides by 5.5 to get r, the rate, on its own. That would show you how many miles Dave drove each hour, on average.
220/5.5 = r * 5.5/5.5