What is the unit rate for meters per second if a car travels 238 meters in 17 seconds?

I assume a unit rate is simply ms^-1 or whatever.

In order to determine m/s one must make the "per whatever" part equal to 1. In this case it is seconds, so we must make seconds equal to 1.

If in 17 seconds it travels 238 metres, that means in 1 second it travels 238/17m=14m

Therefore the unit rate (speed) of the car is 14m/s or 14ms^-1

Well, first of all, any statement with per means over, or divided by. Per means divided by (/). So this is basically saying meter/second. Now , you have to insert the figures. So it will then be 238 meters/17seconds. So;
238/17. 238 divided by 17 is 14. 
   So the answer is 14, and it's unit is m/s because they were divided. So it is 14m/s.
   Hope i helped. Have a nice day.