Slope-intercept form is y = mx + b, where m is the slope of the line and b is the y-intercept.
Since we know the slope, plug it into the base equation:
y = mx + b
y = -3x + b
We don't know what b is, so plug the point we have into the equation:
y = -3x + b
1 = -3(1) + b
1 = -3 + b
b = 4
Now that we know b, input it into the partial equation:
y = -3x + b
y = -3x + 4 is the equation of the line.
