Suppose Caterpillar, Inc., has 651 million shares outstanding with a share price of $73.25, and $24.95 billion in debt. If in three years, Caterpillar has 706 million shares outstanding trading for $87.76 per share, how much debt will Caterpillar have if it maintains a constant debt-equity ratio? The amount of debt required in three years will be $ billion. (Round to two decimal places.)