Total votes = 7500. Invalid votes = 20% of 7500 = 1500. Total valid votes = 7500 - 1500 = 6000. Winning candidate got 55% of valid votes. The other candidate got 100% - 55% = 45% of valid votes. Votes for other candidate = 45% of 6000 = 0.45 * 6000 = 2700.