To calculate the slope of the line defined by the points given, we can use the formula for the slope \( m \) between two points \((x_1, y_1)\) and \((x_2, y_2)\):
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
Let's use the first and last points: \((30, 45)\) and \((39, 9)\).
Here, \(x_1 = 30\), \(y_1 = 45\), \(x_2 = 39\), and \(y_2 = 9\).
Now, substituting these values into the formula:
\[ m = \frac{9 - 45}{39 - 30} \] \[ m = \frac{-36}{9} \] \[ m = -4 \]
Therefore, the slope of the line is \(-4\).