Do seat belts save lives?

Do seat belts save lives? A public health researcher conducted a cross-sectional study of fatality outcomes and seat belt use of 100 victims of motor vehicle accidents in a large city over the course of one month. There were a total of 30 deaths. Of the 100 victims, 50 wore seat belts. Of those victims who wore seat belts, 10 died. What is the probability that a victim randomly selected from this group was alive, given that they did not wear a seat belt?