Answer: (hopefully I didn't make a mistake :D )
y=-3+21
Step-by-step explanation: (I can't sketch the graph for you)
First you need to find the slope of the line passing through the points (5,4) and (-7,0). This can be done using the point-slope form of a line.
Point 1: (-7,0)
Point 2: (5,4)
y2-y1=m(x2-x1)
m= (y2-y1)/(x2-x1) = (4-0)/(5-(-7)) = 4/12= 1/3
Now, when two lines are perpendicular, they are negative recopricols. So the slope of the line would be -3.
Since the equation of the line you are trying to find passes through the point (4,9), using point-slope formula again and solve for y.
y-9=-3(x-4)
y= -3x+12+9
y=-3x+21
