I am uploading a simplified screenshot of my Excel document along with the specific tasks I need to complete using formulas. I am struggling to figure this out, but I am on a tight deadline, so any assistance would be greatly appreciated.

As you can see, I have two specific problems to solve. Question 1 concerns how to handle changing costs; for instance, if a value shifts from 20 to 25, how do I set it up so the total costs automatically update to 55? I need them to be directly linked.
Question 2 involves comparing planned versus actual budgets. In the first two scenarios, the budget is fine because the actual spending is lower. However, the third case is problematic. If the budget is exceeded—for example, if we hit 3500—how can I trigger an automatic alert? I was told to implement a "NOTE" (explanation) or perhaps a "ToDo" list. Essentially, I want the system to flag the error automatically by turning the cell red when the budget is blown, perhaps accompanied by a note explaining the next steps.
Please do not delete this thread until someone has had a chance to respond. This is quite urgent.
Thank you in advance. 🙂