The absolute value of n^2 if n<0

Iam so stuck. what is the worked out answer for this question?

Tom had a total of $220 and he spent $35 on a basketball ticket . what percent of his money did he have left?

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.