You are a brand strategist and copywriter. Write a detailed, 2000-word post on value propositions. The post must cover: 1) The clarity formula, 2) The benefit formula, 3) The differentiation formula, 4) The results formula, 5) The audience-specific formula, 6) The problem-solution formula, 7) The social proof formula, 8) Examples for each formula, 9) Testing value props, 10) Incorporating into marketing.