Well, percent (%) means per hundred, and your number is 6. Therefore, you have 6 per hundred, or 6/100. Also, when you have a percent and want to convert it into a fraction, you must divide the percent by 100, so you could just put the six over 100 since the line between the numerator and denominator basically means division.
You didn't give the fourth zero, but the answer is still false. If you have a root or an imaginary number as a zero, then its conjugate is also a zero. So if 8i is a zero, then -8i must also be a zero, and if 4i is a zero, then -4i must be a zero, with those zeros and -4, the number of zeroes exceeds the number of zeroes that a fourth degree polynomial can have.