To write the equation of a line in slope-intercept form (y = mx + b), where \( m \) is the slope and \( b \) is the y-intercept, you can use the values you've provided.
Given a slope \( m = -3 \) and a y-intercept at (0, 1), the equation of the line is:
\[ y = -3x + 1 \]
This represents a line with a slope of -3 that crosses the y-axis at the point (0, 1).