Each team has an attendance of 2.5 million, so the combined attendance of three teams is 2.5 million * 3 = 7.5 million
We-Seat-U sells 60% of the tickets, so they sell 7.5 million * 60% = 4.5 million tickets
At a charge of $1.50 per ticket, We-Seat-U makes 4.5 million * $1.50 = $6.75 million per year.