Which is a property of an angle? has two sides that each extend forever in both directions has two endpoints has two center points has two rays that share a common endpoint

has two rays that share a common endpoint

Step-by-step explanation:

An angle is formed by a two rays that share a common endpoint.  The distance between the two rays is what makes the measure of the angle wider or smaller.  Each ray extends in one direction forever; however since they share an endpoint, the rays do not extend in both directions forever.  There is only one endpoint, not two, and there is only one center point (vertex), not two.

51

step-by-step explanation:

73-22=51 the   mass number minus the amount of protons gives you the amount of neutrons