Marcia Stubern is planning for her golden years. She will retire in 20 years, at which time she plans to begin withdrawing $50,000 annually. She is expected to live for 25 years following her retirement. Her financial advisor thinks she can earn 6% annually. a) How much does she need to have saved when she retires? b) How much does she need to invest each year to prepare for her financial needs after her retirement?