A line passes through the points $P$ and $Q.$ If $P = (-8,2)$ and $Q = (4,-7),$ then write the equation of this line in the form $Ax + By = C,$ where $A$, $B$, and $C$ are integers with greatest common divisor $1,$ and $A$ is positive.
Slope = [ 2 - - 7 ] / [ -8 -4 ] = 9 / -12 = - 3/4
Using (4, -7)
y = - (3/4) ( x -4) - 7 multiply through by 4
4y = -3 ( x -4) - 28
4y = -3x + 12 - 28
3x + 4y = - 16
+1678 
