Please answer this epidemiology and biostatistic questions and show working.

12. Disease X causes lifelong infection in people. Unfortunately, there were 900 new cases of Disease X in Somewhere Town last year, which has a population of 126,400 people. The Somewhere Town Public Health Department noted that 3, 321 people already had Disease X prior to last year. Show your work. a. What is the cumulative incidence of Disease X last year? (1 point) b. What is the prevalence of Disease X this year, if there were no new cases noted and no deaths or migrations? (1 point)