Suppose Caterpillar, Inc., has 655 million shares outstanding with a share price of $ 72.08 comma and $ 24.56 billion in debt. If in three years, Caterpillar has 696 million shares outstanding trading for $ 83.49 per share, how much debt will Caterpillar have if it maintains a constant debt-equity ratio?

What will the amount of debt required in three years be? (in billion)