so the bridge is 2737 meters long.
at a speed of 322 m/min, meaning for for every passing minute, there are 322 meters covered, so we can simply divide 2737/322 to get a "minute" amount, namely 8.5, at 322 m/min, it takes 8.5 minutes to cross it.
now, if we instead are going slower, at 80 m/min, 80 meters to a minute, then it'll be 2737/80 minutes, namely 34.2125.
their time difference is 34.2125 - 8.5 = 25.7125 minutes, so about 25 minutes and 43 seconds.