If you’re solving an NPV or IRR question, the CFO is your initial investment. It’s a negative number.
To keep it simple, think of negative numbers as cash outflows from your bank account. And monies earned from the project as cash inflows so they are positive numbers.
On the exam you might have one year, say year 2 on a 5 year cash flow problem, where there is a further investment required by you in addition to an outflow of money back to you. So in that case, for that year you use the “net” number (positive or negative when you combine the 2 flows, whichever is bigger) as the number for that year. In this 5 year example, the year 5 cash flow is positive because it’s your return of money. For IRR calculations, it’s equal to the annual profit that year PLUS the original investment repaid. So it’s the total residual value of the investment. Cheers good luck you got this