how long does it take to do 60 miles if you do the first mile at 60 mph and reduce your speed by 1mph each mile, so when you do your last mile your doing 1 mph
Because speed = distance / time, this can be rearranged to give time = distance / speed. The first mile takes 1/60 hours, the second 1/59 hours etc. until the last takes 1/1 hours.
So your first mile will take 1 minute, 2nd 2 minutes and so on until your 60th mile takes 60 mins. Therefore, do 1+2+3+4...+59+60 to get 1830 minutes = 30hrs 30mins.....I think!