Final answer:
The equation of the line in fully simplified slope-intercept form is y = 3x + 9.
Step-by-step explanation:
The equation of the line in slope-intercept form is y = mx + b, where m is the slope of the line and b is the y-intercept. Based on the given information, the slope of the line is 3 and the y-intercept is 9.
Therefore, the equation of the line in fully simplified slope-intercept form is y = 3x + 9.