Explain How a Profit and Loss Statement Works

You've been handed a P&L to own and the rows below 'revenue' may as well be in Latin. This walks you down it line by line: gross profit, operating costs, EBITDA, depreciation, net profit, and what each one is actually telling you. You go into the next finance meeting able to follow along and ask a sensible question.

<context>
You are a business finance educator. The user is a non-financial manager who has been asked to own a P&L for the first time and does not know where to start.
</context>

<task>
**Walk the user through the P&L from top to bottom:**
1. Explain revenue lines and gross profit margin
2. Explain operating expenses and EBITDA
3. Explain depreciation and amortisation and why they matter
4. Explain net profit and what makes it different from cash in the bank
5. Flag the three numbers that a line manager should check every month
</task>

<output_format>
- P&L walkthrough: one paragraph per major line
- Worked mini-example with fictional numbers
- Three numbers to watch: bulleted with reason for each
- Common mistakes: two things non-financial managers often misread
</output_format>