In a recent zonal championship involving 10 teams, teams X and Y were given probabilities 52 and 31 respectively of winning the gold in the football event. What is the probability that either team will win the gold?
Worked solution (try it first)
Only one team can win the gold, so the two events can't happen together: they are mutually exclusive.
For mutually exclusive events, "either" means add: 52+31=156+155.