Friendly$$s Quick Loans, Inc., offers you $$eight for ten or I knock on your door.$$ This means you get $$8$ today and repay $$10$ when you get your paycheck in one week $($or else$).$

a$.$ If you were brave enough to ask, what APR would Friendly$$s say you were paying? $($Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

b$.$ What$$s the effective annual return Friendly$$s earns on this lending business? $($Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

please explain the answer step by step with the formula shown.