This math topic focuses on calculating the elapsed time, specifically subtracting minutes from a given time and determining the resulting time. Problems require subtracting durations between 30 to 100 minutes from specific moments on a clock, with the challenges framed at a five-minute resolution. Each question provides a start time and asks for the time after subtracting a specified number of minutes, applying skills in time calculation and understanding the effects of negative elapsed intervals on a typical 12-hour clock.