Idon't really understand this can someone explain this to me

Nine more than four times a number is the same as one less than twice the number. find the number?

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.

When the ball has traveled a distance of