Use the slope formula: m = (y2 – y1) / (x2 – x1)
Identify two points on the line: (x1, y1) and (x2, y2)
Subtract the y-values
Subtract the x-values
Divide the change in y by the change in x
Simplify the fraction if possible
If the line goes up from left to right, the slope is positive
If the line goes down from left to right, the slope is negative
If the line is horizontal, the slope is 0
If the line is vertical, the slope is undefined