Answer:
The answer to your question is 3x - y = 3P - Q
Explanation:
Process
1.- Get the points from the graph of the original line
A (0, 5)
B (-3, 6)
2.- Find the slope of the original line

Substitution

3.- Find the slope of the new line
As the lines are perpendicular the new slope will be
m = 3
4.- Find the equation of the new line
Point (P, Q)
Equation y - y1 = m(x - x1)
Substitution
y - Q = 3(x - P)
Simplify
y - Q = 3x - 3P
Result
3x - y = 3P - Q