From January 1, 2021, the price of petrol (in Rupees per litre) on m^th day of the year is 80 + 0.1 m, where m = 1, 2, 3, ..., 100 and thereafter remains constant. On the other hand, the price of diesel (in Rupees per litre) on n^th day of 2021 is 69 + 0.15 n for any n. On which date in the year 2021 are the prices of these two fuels equal?