Here we need to remember the general movement equation:
distance = speed*time.
The plot can be seen at the end, and the equation of motion is:
p(t) = 4.3m + (6.7m/s)*t
Let's define p(t) as the function that gives the position of the horse at the time t.
We know that the position of the horse at t = 0s is:
p(0s) = 4.3m
We also know that the horse has a velocity of 6.7 m/s, then using the distance equation we can write the position as:
p(t) = 4.3m + (6.7m/s)*t
This is a linear equation with a y-intercept of 4.3m and a slope of (6.7m/s).
This is the corresponding equation of motion.
The plot of this can be seen below, where we just draw the line between t = 0s and t = 5s.