What is the nominal interest rate per week? Per year

After losing money playing on-line poker,
Scott visits a loan shark for a $750 loan. To avoid a visit from the
collection agency, he will have to repay $800 in just one week.
A. What
is the nominal interest rate per week? Per year?
B. What
is the effective annual interest rate?
Topic: Effective
Interest Rates
Level of difficulty: Medium