To find the slope \( m \) of a line that passes through the points \( (x_1, y_1) = (2, 4) \) and \( (x_2, y_2) = (0, 8) \), we can use the slope formula:
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
Substituting in the values:
\[ m = \frac{8 - 4}{0 - 2} \] \[ m = \frac{4}{-2} \] \[ m = -2 \]
Thus, the slope of the line is \( -2 \).