When 36 people are seated the room is 2/3 full.
So for 1/3 , 18 people are needed
It will be 3/3 full if 54 people are present
So there can be 54 people in total
Now for the room to be 1/2 full , people will be 1/2 x 54 = 27 people
Perpendicular lines have the negative reciprocal slope, so the slope of your new line will be -1/4 and the current equation will be as follows:
y = -1/4x + b
(where b is the y intercept)
to find b, plug in point A and you'll get:
2 = -1/4(16) + b
2 = -4 + b
6 = b
the equation will be:
y = -1/4x + 6
Answer
Root-(-12,0)
Vertical intercept- (0,6)