Final answer:
To find the balance of Kate's lunch account after the 5th day, subtract the amount she spends each day from her initial balance of $7. However, the balance cannot be negative, so it is not possible for Kate's lunch account to have a balance of -$8.
Step-by-step explanation:
To find the balance of Kate's lunch account after the 5th day, we start with her initial balance of $7 and subtract the amount she spends each day for 5 days. Since she spends $3 each day, we multiply $3 by 5 to get a total of $15. Finally, we subtract $15 from her initial balance of $7 to find the balance after the 5th day.
The balance after the 5th day is ${{7-3*5=7-15=-8}}.
However, it's important to note that the balance cannot be negative, so it is not possible for Kate's lunch account to have a balance of -$8.