A sociology teacher asked his students to complete a survey at the beginning of the year. One survey question asked, "Do you have a job?"Another question asked, "Do you study more than 5 hours a week?" The probability that a student worked is 0.7, the probability that a student studies more than 5 hours a week is 0.3 and the probability that a students works and studies more than 5 hours per is 0.2.