The owner of an apartment tower leases each of her 250 apartments for the sum of $ 300 per month. She knows that if she decreases the rent in increments of $ 2, she earns an average of 5 tenants. What should the average monthly rent for one of these apartments be if she wants to make a monthly marimal income? What should be the number of tenants necessary to obtain this marimal income? What should this marimal income be?