The answer is 45 miles per hour. The unit rate (r) is the number of miles (d) divided by the number of hours (t): r = d/t. We know that d = 135 miles and t = 3 hours. So, the unit rate is r = 135 miles/3 hours. r = 135/3 miles per hour. r = 45 miles per hour. The unit rate is 45 miles per hour.Hope this helps. Let me know if you need additional help!