5X and X +5 help ASAP

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?  

How many solutions does the nonlinear system of equations graphed bellow have?

If the scale factor between two circles is 2x/5y what is the ratio of their areas?