A charter flight charges a fare of $300 per person plus $10 per person for each unsold seat on the plane. The plane holds 100 passengers. The total revenue received can be modelled by R(x)=-10x squared 700x 30,000, where x represents the number of unsold seats. The maximum revenue is $__ ,which occurs when __ seats are left unsold. How do I find the maximum revenue and the number of seats left unsold?