How can I find the net fixed assets if the only numbers I have are long term debt ratio, current ratio, current liabilities, sales, profit margin, and Return on Equity?

Have you made an attempt?
Use current ratio to compute the current assets
Calculate profit using sales and profit margin
Use the profit margin to compute the equity applying ROE
Use the debt ratio to compute the long term debt.

Put all these figures in a skeleton balance sheet and you will get the balancing figure as net fixed assets