Can y’all help with number 16 pls

You can find the constant of proportionality by finding the ratio of

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.

What is the frequency of the sinusoidal graph?