Profit can't go to salaries, or else it wouldn't be profit.

If the question is actually revenue, it completely depends on the business. How much marketing, sales, support etc the software requires.

Should be what percentage of revenue should go on pay.

Profit is what is left once all costs have been taken from revenue.

Have a look at how W. L. Gore and Associates is structured sometime.

Trick question.

Profits are calculated after salaries are paid.