statistics

There are three TAs at STAT class Office hours: Tom, Jackey, and Jackson. Two students arrive at office hours at different times when the TAs are helping no other students. It is assumed that the students then approach a TA for help at random and independently of one another. Let X and Y be defined as follows: X = # of times Jackey is asked for help Y = # of times Jackson is asked for help 1. Given that no students have asked Jackey for help, what is the probability that no students have asked Jackson for help