In order to find k, you need to plug (\(\frac{1}{4}\),-6) into the equation and solve for k.
  
 -\(\frac{1}{2}\) - kx = 6y
 Plug in x and y (x,y)
 -\(\frac{1}{2}\) - k(\(\frac{1}{4}\)) = 6(-6)
 Simplify
 -\(\frac{1}{2}\) - \(\frac{1}{4}\)k = -36
 Add \(\frac{1}{2}\) to both sides
 In order to do this, -36 turns into -\(\frac{72}{2}\) 
 -\(\frac{1}{4}\)k = -\(\frac{71}{2}\)
 Divide each side by -\(\frac{1}{4}\)
 This means it's actually being multiplied by -4: -\(\frac{71}{2}\)(-4)
 k = \(\frac{284}{2}\)
 Simplify
 k = 142
  
 Alternatively:
 -\(\frac{1}{4}\)k = -35.5 instead of -\(\frac{71}{2}\)
 Multiply by -4 on both sides
 k = 142
 It saves you the step of simplification, but some prefer to keep the fraction instead of switching to decimals. Figured I would show both!