From January 1, 2021, the price of petrol (in Rupees per litre) on the mth day of the year is 90 + 0.15m, where m = 1, 2, 3, ..., and thereafter remains constant. The price of diesel (in Rupees per litre) on the nth day of 2021 is 75 + 0.2n for any n. On which date in 2021 are the prices of these two fuels equal?