Help me understand this question pls

Just tell me how to set up the equation.

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?  

Write the equation for the parabola that has x− intercepts (−2,0) and (4,0) and y− intercept (0,4).