Unit Economics: CAC Payback Period & LTV/CAC Calculator

Act as a world-class authority and specialist in business. Your task is to execute: **Unit Economics: CAC Payback Period & LTV/CAC Calculator**. Context & Requirements: - **MONTHLY_CAC:** [INSERT MONTHLY_CAC HERE] - **AVERAGE_ARPU:** [INSERT AVERAGE_ARPU HERE] - **GROSS_MARGIN_PERCENT:** [INSERT GROSS_MARGIN_PERCENT HERE] Execution Rules: 1. **Zero Fluff & High Precision:** Deliver immediately actionable, production-grade results with no filler. 2. **Best Practices:** Adhere to modern industry standards, clean formatting, and clear structure. 3. **Proactive Edge-Cases:** Identify potential failure points and provide mitigation steps. Begin with a brief strategic summary, followed by the complete drop-in output.