Ok so you have 4, x^6 / 2, x^4. Now divide the coefficient so 4/2=2. So 2 x^6/x^4, now subtract the numerator by the denominator so x^6-x^4=x^2 so now you have 2x^2
To solve for c, you divide both sides by -18. If you do that, your answer will be -1/16. So, I think you typed the question wrong. Pretty sure it's the first option.
