How do I find the final probability?

In Country X, 20% and 50% of the people are vaccinated with Vaccine A and Vaccine B respectively to protect them from infecting Covid-19. The remaining people are not vaccinated with any Covid-19's vaccine. None of them vaccinated with more than one vaccine. It is known that the rates of infected om Covid-19 for people vaccinated with Vaccine A, people vaccinated with Vaccine B and unvaccinated people are 20%, 10% and 50% respectively. If a person is chosen randome and found to be infected with Covid19, what is the probability that he/she is unvaccinated