The slope of a straight line is the steepness of the line with respect to the x axis.
It is the increase in y coordinate (ordinate) with respect to the increase in the (abscissa) x coordinate, as we move from left to right on the straight line.
The way to find it is : take two points on the line. A(x1,y1) and B(x2,y2)
if x1 = x2, then slope is infinity.
slope = (y2-y1) / (x2-x1)
Slope is also equal to the tangent of the angle made by the straight line L with the positive x axis.
a x + by + c = 0 is the equation. then slope = - a/b