We are told the car is going 25 mi/h and we are told the change in time is 1.5 seconds. We have to change units so that the time is in seconds, or hour. I will be doing this problem in seconds.
Converting mi/hr to mi/sec, we have to use dimensional analysis. Since there are 3600 seconds in an hour, we divide 25 by 3600. This will give us mi/sec
Now that all our units match, we can just multiply by 1.5 seconds.
0.01041667mi