Answer: 
Step-by-step explanation:
Slope of two lines that are perpendicular to each other is 1.
If one line is
, then its slope = 3 [by comparing to the linear equation y= mx+c, here m=3]
Let n be the slope of the required line, then

Equation of line with slope n and passers through (a,b) is

Equation of line with slope n=
and passes through point ( 0,-4) :

Hence, Required equation : 