Answer:
y = 3x - 18
Step-by-step explanation:
The given line, y = -3x + 9, has slope -3. Any new line perpendicular to this has slope +3/1, or just 3.
Start with the general slope-intercept form of the equation of a straight line:
y = mx + b. Now substitute 9 for y, 9 for x and 3 for m:
9 = 3(9) + b. Then b = -18, and the desired equation is y = 3x - 18.
