We can calculate the slope by substituting the given points into the Slope Formula.
slope = y_2-y_1/x_2-x_1
Note that it does not matter which point we choose to use for ( x_1, y_1) and ( x_2, y_2), since the result of using the Slope Formula will be the same.
The slope of the line that passes through the given points is - 2.
Extra
Switch Order of Points
We will confirm that it does not matter which point we choose to use for ( x_1, y_1) and ( x_2, y_2). To do so, let's change the order of points in our formula. This time we will use (2.5,-5) for (x_1,x_2), and (2.1,-4.2) for (x_1,x_2).
