Final answer:
Peter is likely reading the 'job responsibilities' section of his job description, which details the duties associated with his new role, including budget management and financial authority.
Step-by-step explanation:
If Peter is promoted from a first line manager to a middle manager and is reviewing his job description regarding the level of expenditure in his budget, it is likely that he is looking at the job responsibilities section. This section typically outlines the duties associated with a position, including those that pertain to financial management and budgeting. The job responsibilities tend to describe not only the tasks and duties one is expected to perform but also might include specifics such as budget management and oversight which would give Peter the details on his allocated resources and financial authority.