Solve picture that I provided

When are two distinct non vertical lines parallel

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?  

Alarger number is double the sum of a smaller number. the larger number is 2 less than 3 times the smaller number. if y represents the larger number and x represents the smaller number, which equations model the situation