Is the line through points p(-3,-2) and q(2,3) perpendicular to the line through points r(10,1) and s(15,-6)?

The slope of line PQ is m1 = ( 3 - (-3) ) / (2 - (-2) ); then m1 = 6/4 = 3/2;
In the same way, the slope of line RS is m2 = -7/5;
But (3/2) x (-7/5) = -21/10, which is diferrent from - 1;
So, the lines aren't perpendicular.

Just a second zzz