In animals like Annelids, Molluscs, organs have associated to form functional systems, each system concerned with a specific physiological function. This pattern is called ________ system level of organization.
A person goes from point N to P and comes back. His average speed for the whole journey is 60 km/hr. If his speed while going from N to P is 40 km/hr, then what will be the speed of the person (in km/hr) while coming back from P to N?