Final answer:
The formula d = kt represents direct variation, where the distance traveled (d) is directly proportional to the time taken (t) with a constant rate of change represented by the constant k.
Step-by-step explanation:
The kind of variation represented by the formula d = kt is direct variation. In direct variation, one variable is a constant multiple of the other variable. In this case, the distance traveled (d) is directly proportional to the time taken (t), with a constant rate of change represented by the constant k.
For example, if k = 50, and t = 2, then d = 100 km.
Similarly, if t is halved to 1, then d is also halved to 50 km.