To find the equation of the line through the origin that describes the proportional relationship shown in the graph, we need to determine the slope \( m \) of the line passing through the points \( (1, 4) \) and \( (2, 8) \).
First, we can calculate the slope \( m \) using the formula: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] where \( (x_1, y_1) = (1, 4) \) and \( (x_2, y_2) = (2, 8) \).
Substituting in the values:
\[ m = \frac{8 - 4}{2 - 1} = \frac{4}{1} = 4 \]
Since the equation of the line through the origin is in the form \( y = mx \), we can substitute the value of \( m \):
\[ y = 4x \]
Thus, the equation of the line is \( y = 4x \).