If you're ever confused on why the budget isn't positive, then this article is for you!
In the above screenshot, the remaining budget is negative because of over-allocation of the budget.
Edit your ad campaign budget allocation by the amount of money over budget to get a positive remaining budget.
NOTE: The $29 for the Email Campaign Expense will appear regardless if you have an email campaign. This is to represent an email subscription fee that your company may have.
In the case of the screenshot above, they are over budget by $529.
In this situation, the student needs to lower or reduce the budget of at least one of their campaigns by $529. To do this, click on the link in the red warning that says "Jump to Ad Campaigns". From here, simply click the edit button for a campaign under the Campaigns tab and lower it by $529.