Just help me please its due today

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?  

5,678.321 what place value is the 1 in

Which line is parallel to a line that had a slope of 3 and a y intercept at (0,0)