The distance traveled varies directly with the time spent in motion when speed is held constant. if d represents the distance traveled and t represents time, which equation would represent this variation?

Direct proportionality occurs when an increase quantity or a variable causes a corresponding increase in another variable and vice versa. In this case, when distance increases it causes an increase in time taken if speed is kept constant.
Therefore, d α t
 mathematically; d = kt , where k is a constant,
Hence; d = st since s is the constant.
Therefore the equation will be d= st