input: Write a function to calculate the total amount of time spent by a user on a website in minutes.
  assert total_time_spent([120, 60, 90, 5, 10, 45]) == 5.416666666666667
  assert total_time_spent([300, 200, 100]) == 10.0
  assert total_time_spent([60, 60, 60]) == 3.0
output: def total_time_spent(durations):
      return sum(durations) / 60