Final answer:
Xavier's account will have a balance of -$445 at the end of the month.
Step-by-step explanation:
The balance in Xavier's account at the end of the month can be calculated by subtracting the bank fee from his initial balance. Since the fee is $750 and his balance is $305, we need to determine if the fee applies. If his balance is below $500, the fee will be charged. If it is above or equal to $500, no fee will be charged.
In Xavier's case, since $305 is below $500, the fee will be charged. Subtracting $750 from $305 will result in $-445. Therefore, at the end of the month, Xavier's account will have a balance of $-445.