First, you have to find the midpoint of the two endpoints, using the formula, (x1+x2 divided by 2, y1+y2 divided by 2).
Next you substitute x1 for 0 and x2 for 2, so therefore your first point will be 1 after dividing by 2. Next you have to substitute 0 for y1 and 3 for y2 after this you divide by 2 and you get 3/2. So the midpoint of (0,0), (2,3) is (1,3/2).
Now you have to find the midpoint of (5,0), and (6,3), this would be the exact same process and you would end up with (11/2, 3/2) as your midpoint for (5,0), and (6,3).
Now all you do is find the slope between, (1,3/2), (11/2, 3/2).
The formula to find the slope is m=y2-y1 divided by x2-x1.
So now 3/2-3/2 divided by 11/2-1. This give you a slope of 0.
So in conclusion the answer is 0.
I hope this helps!