Here it was a case of direct proportion in which if two things are directly proportional to each other. If one thing thing increases then the value of second also increases. Here if the time increases then the distance also increases
2.4 minutes is 144 seconds. divide -216.12 by it to get altitude per second. This is 1.5 meters per second. Multiply this by 60 to get the rate per minute, totaling 90.05 meters per minute. Sorry if this explanation was long that was how I remember.