Atrain travels at a constant speed. what is the train's speed between checkpoints, expressed as a unit rate? use the information given in the picture to you.

Remember that the speed is the rate of change of the position with respect to time, so to solve this we are going to use the kinematic equation: 
where 
is the speed of the train
is the initial distance
is the final distance 
is the initial time 
is the final time 

Since checkpoint A is the initial checkpoint, we can infer that  and . Similarly, since checkpoint B is the final checkpoint, we can infer that  and . Lets replace the values in our kinematic euation:



mph

We can conclude that the train's speed between checkpoints is 60 mph.