The basic formula is d = r * t. The units are important. Time is usually recorded as seconds. d can be feet or meters in standard form. The formula has to be rearranged to get r by itself.
r = d/ t
d = 20 feet
t = 30 seconds
r = 20 feet / 30 seconds
r = 20 ft/sec
Even though you are told not to enter the units, it is still important to recognize what they are.
