In order to solve this problem, use sign conventions. Since deposit indicates cash inflow, that would take the positive sign. On the other hand, withdrawals take negative sign. We add these integers to the original balance. he solution is as follows:
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.