Question 143799
Find the slope of the line through the points first:

{{{m=(y2-y1)/(x2-x1)=(-6-4)/(-3-0)=-10/-3=10/3}}}
Now, orthogonality for lines is made by simply taking the negative reciprocal. That is, -3/10 will be the slope of any line perpendicular to the line through the points you supplied.

Just for fun let's write the equation for such lines as well and graph it.
original line: y=(10/3)x+4
And a perpendicular line would simply be y=(-3/10)x
{{{graph( 300, 200, -5, 5, -5, 5, (10/3)x+4, (-3/10)x)}}}