A transport company maintains a fl eet of lorries for carrying goods from Chennai to Trichy, 300 km off. Each lorry, which operates 20 days on an average in a month, starts every day from Chennai with a load of 10 tonnes and returns from Trichy with a load of 8 tonnes. Calculate the total commercial tonne-km and cost per commercial tonne-km. The total monthly charge for a lorry is Rs. 1,62,000. What rate per tonne should the company charge if it plans to earn a gross profi t of 25 per cent on the freightage?