The slope of any line is the fraction [tex] \frac{\Delta y}{\Delta x} [/tex], where [tex] \Delta y [/tex] is the change in y-coordinate and [tex] \Delta x [/tex] is the change in x-coordinate.
To find these changes, we take the difference of the corresponding x and y coordinate for the two points. Here, our y-coordinates are -7 and 3, and our x-coordinates are 5 and 1, so our slope is
[tex] \frac{-7-3}{5-1}=\frac{-10}{4}=\frac{-5}{2} [/tex]