how to calculate the internal growth

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?

Income Statement

Sales = $16,200

Costs = 10,400

Taxable income = 5,800

Taxes (40%) = 2,320

NET INCOME = 3,480

BALANCE SHEET

Current assets = 10,100

Fixed Assets = 26,500

TOTAL ASSETS = 36,600

Debt = 16,400

Equity = 20,200

TOTAL LIABILITIES/EQUITY = 36,600