Find the diameter of a circle whose circumference is 18.85

I’m stuck on this i don’t understand.

Multiplying an even number of negative numbers gives an answer that is choose from:

Aschool puts on a play. the play costs $1,200 in expenses. the students charge $4.00 for tickets. there will be one performance of the play in an auditorium that seats 500 people. what is the domain of the function that shows the profit as a function of the number of tickets sold?