X+(x-5) +(x-10) ... This adds up to 8x -140 seconds where x is the 1st race time. This adds up to 44:20 minutes 44mins * 60 sec/min = 2640 seconds + 20 = 2660 seconds cummulative 8x - 140 = 2660 8x =2800 sec 8x = 350 seconds or 4.5mins for the 1st race Race 2: subtract 5 seconds yields 4 mins 25 seconds