If you earn $40 a year on a $500 investment, what is the annual rate of return?

Can someone plz me understand how to do these. plz, show work. in exercises 1-4, rewrite the expression in rational exponent form.[tex]\sqrt[4]{625} \sqrt[3]{512} (\sqrt[5]{4} )³ (\sqrt[4]{15} )^{7}\\ (\sqrt[3]{27} )^{2}[/tex]