Since speed is equal to the distance traveled by time so, the formulas of time, speed and distance are dependent on each other. With the known values of any two the unknown can be calculated. The below given is the time formula using speed and distance to calculate the time. According to this time formula just dividing the distance by speed gives the time. The resultant unit of time calculated will be dependent on the units of speed and distance you use.
The above time formula using speed and distance is just a simple physics formula which can be remembered and derived easily.