Hello, can you help me please. I don't understand this homework. ​

Look at the following graph of the given equation. determine whether the equation is a function. explain why or why not.

Oscar and julie ashton are celebrating their 15th anniversary by having a reception hall. they have budgeted $4,500 for their reception. if the reception hall charges a $90 cleanup fee plus & 36 per person, find the greatest number of people that they may invite and still stay within their budget.

Which one ? is the answer and how to find this answer