Which of the following equations can be used to find the internal rate of return (i) for a project that has an initial investment of p, net annual cash flows of a, and a salvage value of s after n years?
1) i = p + a + s + n
2) i = p - a - s - n
3) i = p / (a + s + n)
4) i = (a + s + n) / p
