Assets and costs are proportional to sales. Debt and equity are not. The company maintains a constant 30 percent dividend payout ratio. What is the

So i tried to solve this question and i was wondering if someone could tell me if i did it correctly. This would be greatly appreciated.

Assets and costs are proportional to sales. Debt and equity are not. The company maintains a constant 30 percent dividend payout ratio. What is the internal growth rate? I—-I-_–