Whenever you are looking for a line that is perpendicular to another, you have to change the slope of the line you are given. First, find the reciprocal of the slope and then make it negative.
In your case, the slope would be -4.
Now you can use point slope form to solve your problem.
Point Slope Form: y - y₁ = m( x - x₁)
y - 6 = -4( x - 0)
y - 6 = -4x + 0
+ 6 + 6
----------------------
y = -4x + 6
The final answer is y = -4x + 6.
