The formula d = rt describes distance traveled in time and rate of speed. However, we only have the distance and time to place in. This means d = rt would become d / t = r. Once filled in, the problem is now 76 / 1.5 which equals 50.6 (repeating bar over the 6). However, this is the AVERAGE speed of the truck (meaning we are rounding. 50.6 rounded to the nearest speed would be 51 miles per hour.