Please help

II$.$ Your division is considering two investment projects, each of which requires an up$-$front expenditure of $$25,000.$ You estimate that the cost of capital is $10$ percent and that the investment will produce the following after$-$tax ash flows:

$\backslash$table$[[,,],[$Year$,$Project A$,$Project B$],[0,-25000,-25000],[1,5000,20000],[2,10000,10000],[3,15000,8000],[4,20000,6000]]$

a$)$ What are the payback periods of the two projects? You have to show how to get your answer$-$

b$)$ If the projects are independent $($non$-$mutually exclusive$)$ and the cost of capital is $10$ percent, which project $($s$)$ should the firm undertake? Answer this question with NPV and IRR of those two projects. You have to show bow to get your answer.