b$.$ Compute the internal rate of return that can be earned from a mining venture from the following cash flows: Compute the discounted cash flows at $20\%$ and $25\%$ discount rates, present values and arrive at the possible IRR $(12$ marks$).$

$-9$

$\backslash$table$[[$Year$,$Investment,Earning$],[0,100,],[1,40,],[2,,20],[3,,80],[4,,90],[5,,90]]$