I need some help and clarifications on such problems. For example:

A student thinks he will succeed on subjects "Probability", "Statistics" and in both of them with the probabilities 0.7, 0.6 and 0.5 respectively. Find the probabilities:

1). p1: The student will succeed at least in one of the subjects

2), p2: The student will succeed only in one of the subjects

3), p3: The student will succeed not more than in one subject

result: p1 = p2+p3

:)