Please help me find the missing answers

Of the 55 students enrolled in a statistics class last semester, 20 used an online software and 30 attended classes regularly. 10 of those who used an online software also attended classes regularly. Report answers accurate to 4 decimal places. 1. What is the probability that a randomly selected student from the class: a) did not use an online software? | 0.6364 b) used an online software but did not attend classes regularly? | 0.1818 c) either used an online software or attended classes regularly? neither used an online software nor attended classes regularly? | 0.2727 2. If two students were selected from the class, one after the other and without replacement, what is the probability that: a) the second student attended classes regularly given the first student also did? b) the second student attended classes regularly given the first did not? c) both students attended classes regularly? |0.2929 d) only the first student attended classes regularly? | 0.2525 e) only one of the two students attended classes regularly? f) neither of the two students used an online software