Question 36296
What formula do I use to find an equation for the line with y-intercept 3 that is perpendicular to the line y=2/3x-4?

I came up with the answer 2y=-3x+6 using y=x/2+K.
My Gradient is -3/2
y=-3/2x + 6/2
2y=-3x + 6.
Is this correct? 
Thank you for your help.

Looks good.  Your line has a slope of -3/2 and y-intercept
of "3" which is what you are looking for.
Cheers,
Stan H.