Suppose Caterpillar, Inc., has 658 million shares outstanding with a share price of $75.47, and $25.39 billion in debt. If in three years, Caterpillar has 697 million shares outstanding trading for $82.88 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.)