Dorothy invested $$250,000$ in a rental property. She earns net revenue of $$50,000$ per year from the property, If she keeps the property for $10$ years, what is her rate of return? $($Here$,$ assume the salvage value is $0)$

A company is planning to purchase a new machine to meet increased demand. Both options under consideration have useful lives of $10$ years and no salvage value at the end. Cash flows for both are as follows:

$\backslash$table$[[$Machine$,$Initial Cost,$\backslash$table$[[$Annual$],[$maintenance$],[$costs$]],$Annual income$],[$A$,400,000,20,000,80,000],[B,650,000,30,000,160,000]]$

Use NPV analysis to determine which machine would be a better option. Interest rate is $8\%.($Hint: first compute the net annual benefit $=$ annual cost $-$annual income$)$