Final answer:
The expression that represents how much money the Baker family had after x days is 7000 - 100x.
Step-by-step explanation:
The expression that represents how much money the Baker family had after x days is
Since they spend $100 each day, the amount spent after x days would be 100x. To find the amount of money they had left, we need to subtract the amount spent from the initial amount they had, which is $7000. This can be represented as 7000 - 100x.