I believe the answer is c ,BECAUSE... to find the change you take 5000 multiply it by the numbers that if aded would equal 5600 and 5000 times .12= 600, 5000 +600= 5600 hence the number of population in 2010.
hope I helped
x=15-657/2=15-373/2=-5.316
x=15+657/2=15+373=20.316