Why is the slop on a distance time graph speed?

Answer 1

When looking at a distance vs. time graph, it shows how far an object is traveling over a certain amount of time which can be written like this:

distance per time or distance/time (distance divided by time)

If we then put units in for distance (let's say meters) and time (seconds) we get this:

meters/seconds

which is the same as the units for speed.