How do I find out what the net income is, when it is not stated. I Know that net income= revenues-expenses, and that profit margin = net income/sales. I have the expenses figures, but not the revenues or net income figures.

Technically, I don't think you have enough information to determine the net income.

Assuming you are talking about selling something (lets say widgets), you could try and derive the net income by plugging in some values that you think are reasonable and accurate but that's just making an educated guess. You could improve the accuracy of this guess by researching the products and getting a better feel for the profit margins by learning what the wholesale price is and then the retail price. Then all you need to do is estimate the total number of sales and that should lead you to your net income then subtract the expenses.

What do you know about the expenses? That might contain some clues that could be useful...

Do you have that profit margin you mentioned? You can figure it out with that.