From January 1, 2021, the price of petrol (in Rupees per litre) on m' day of the year is 80 + 0-1m, where m = 1, 2, 3, …., 100 and thereafter remains constant. On the other hand, the price of diesel (in Rupees per litre) on nth day of 2021 is 69 + 0-15n for any n. On which date in the year 2021 are the prices of these two fuels equal ?