Method 1
Open the brackets, making sure you've spotted the minus sign just outside them which will change the minus sign inside to a plus. The equation becomes 6x-x^2+5x=0. Bring together similar terms, which means the equation becomes 11x-x^2=0. But x is a common factor so this can be written x(11-x)=0. Therefore x=0 or 11. The only option permitting this solution is d, x=0; you may have spotted this solution when you first looked at the question, because x shows itself as a common factor in the original question, but you wouldn't have so easily spotted that another solution is x=11.
Method 2
Another approach would be to simply substitute each option value into the equation and pick the only one that makes the expression zero. Is that what your tutor or examiner wanted you to do?