Calculate the debt service coverage ratio (DSCR) for Company Visa Inc., which had net operating income of $18.79 billion and total debt service of $3.25 billion. Explain the debt service coverage ratio (DSCR) as a financial metric used to assess a company's ability to meet its debt obligations with its operating income. Discuss the significance of DSCR in evaluating financial solvency and debt repayment capacity.