Plz, help me with the question in the photo.

How many $20 bills do you need to have to make $280

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?  

Find the area of the triangle shown 3 by 6