Can you please explain this?

Consider an economy with three types of jobs. The table below shows the jobs, the frequency with which vacancies open up on a yearly basis, and the lifetime income associated with each job. Assume that once you secure a job, you work there till the end of your life. Searching for a job costs $D per year and generates at most one job offer. There is a 20 percent chance of not receiving an offer in a year. Job Type Frequency Income A 30 percent $60,000 B 20 percent $100,000 C 30 percent $80,000 As a function of D, specify the optimal job search strategy (the optimal asking wage, R) if the worker maximizes her expected income net of search costs