Explanation:
a. 
In ten years 2010 2020
Population 38655 41204
41204 - 38655 = 2549 (that's in ten years) 
In one year = 254.9
The equation is :-
 P: stands for population 
t: stands for number of years 
 
P = 38655 +/- 254.9t ###
b. 
Substitute in the equation we're going to substitute with the positive term +254.9t because logically 50000 is more than 38655 which were in 2010
50000 = 38655 + 245.9t
Then t = 44.5 years 
 That's will happen in 2010 + 44.5 = 2054.5 ###
 That's approximately in 2055 ###