this time is how we calculated the Distance over something. If we want the slope of A and B

we take the coordinates (0,3) (4,6)  and we use the equation m=y2-y1/x2-x1 or m=y1-y2/x1-x2 so get the slope=3/4

Then take the equation y=mx+b and put the slope in the equation: y=3/4x+b.

After successfully completing these steps you choose one of the two coordinates and replace the y and x with them.

6=3/4×4+b

which gives us the y-intercept/b

3=b

and there we have everything.