a smart phone reseller receives a shipment of 250 phones of a new model at a retail store. the exponential function n(t)=250(2)-t gives the number of phones,n,left after t hours. what is the meaning and value of n(0) n(2)?n(10)

They are simply asking how many phones came in after a certain amount of time in what appears to be an equations saying that 250 phones are coming in per hour.

In the equation n(t) = 250(t)

You would simply replace the t on both sides of the equation with the time and derive the number of phones that came in after a certain amount of time.