For 2 nights cost is $10,000 for theater rental, insurance, and musicians. 10% of $10,000 is $1000 that goes to theater if $10,000 worth of ticket is sold, which is to break even. Now the break even cost is $10,000+$1000= $11,000. Cost of one ticket is $10, to break even the total cost, number of tickets that must sell is $11,000 divided by $10, which is 1100 tickets. 1100 tickets must sell in total for two nights to break even.