HELP NEEDED!! I don’t understand

Slope = - 2.5

Step-by-step explanation:

A right angled triangle is drawn to meet the best fit line at any point on the graph,, the point at which the triangle meets the best fit line, provides the values for the rise and run used to calculate the slope, the ris ubsyge cgbage in y values and run is the change in x values ;

Rise, y2 = - 1 ; y2 = 4

Run ; x2 = 3 ; x1 = 1

Rise = y2 - y1 = - 1 - 4 = - 5

Run = x2 - x1 = 3 - 1 = 2

Slope = Rise / Run = - 5 / 2 = - 2.5