Answer: The required number of tickets sold for the semi-final matches is 12270.
Step-by-step explanation: Given that 49080 tickets have been sold for the tournament.
of the tickets are for the qualifying matches and 15% of the tickets are for the final match.
We are to find the number of tickets that sold for the semi-final matches.
Let s denotes the number of tickets that are sold for semi final matches.
According to the given information, we have
Number of tickets sold for the qualifying matches is

and the number of tickets sold for the final match is

Therefore, we must have

Thus, the required number of tickets sold for the semi-final matches is 12270.