Final answer:
Sitiveni's checking account balance becomes -$57 after writing a $30 check since he had a starting balance of -$27.
Step-by-step explanation:
If Sitiveni starts with a -$27 balance in his checking account and then writes a check for $30, the balance in the account will be the sum of these two amounts. Writing a check removes money from your account, which means you add the negative amount of the check to your current balance. So you calculate the new balance by adding (-$27) + (-$30), which equals -$57.
To illustrate, think of the negative balance as a debt that Sitiveni owes to the bank. If he writes a check for another $30 without depositing any money, he is increasing his debt (or his negative balance).