This document explores key concepts in corporate finance, including investment analysis and capital structure. It examines the payback period rule, net present value (NPV), and internal rate of return (IRR) as methods for evaluating investment proposals. The document also delves into the Modigliani-Miller (M&M) propositions, which provide insights into the relationship between capital structure and firm value. Through calculations and explanations, the document demonstrates how to apply these concepts in real-world scenarios.