I am having major issues with this problem, even with starting it. I have a test coming up and this is an example. I actualy have 3 questions but this is the first.

The population of a midwestern city follows the exponential law.
a.) If N is the population of the city and t is the time in years, express N as a function of t.

b.) If the population decreased from 800,000 to 700,000 from 2003 to 2005, what will be population in 2007.