He drank 2329.6 mL of water on Tuesday. If he drank 1280 mL on Monday and increased it by 82%, it would be 2329.6 mL. 82% of 1280 mL is 1049.6 mL, then I added 1049.6 mL and 1280 mL together to get a total of 2329.6 mL. His increase (82%) was 1049.6 mL.