1) If the coordinates all lie on a line that has the same y coordinate, then the line is horizontal, and the slope is zero.
2) If the coordinates all lie on a line that has the same x coordinate, then the line is vertical, and the slope is undefined. 3) Lines that are diagonal and travel UP to the RIGHT have positive slope. (the line will also travel DOWN to the LEFT ) 4) Lines that are diagonal and travel DOWN to the RIGHT have negative slope. (the line will also travel UP to the LEFT ) 
Set A) in given example is a diagonal line with positive slope
Set B) in given examples is a horizontal line Set C) in given examples is a diagonal line with negative slope Set D) in given examples is a vertical line 
The following will show the related intercepts, slopes, and equations of the lines in each set of five points
