Team A has 60 students.
4 are eliminated by their own team hence chance of getting eliminated by A team is 4/60 and 2 are eliminated by team B. Hence chance of eliminating A's team by B team is 2/60
Hence toatal chance of eliminating A's team memeber is 4/60*2/60= 1/15*1/30= 1/145
Similarly, for B team the total probability of elimination is 3/20*1/20= 3/400