Write 5 equations where the sum is equal to 9

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?  

Me find the value of x each figure.

What does independent variable and dependent variable mean in math?