We know that the equation will have 23,000 in it, since that was the population in 2012. It's increasing at a rate of 2%. To show an increase, divide 2 by 100 and add a 1 on it. It'll be 1.02=102%. You'll be powering that number by however many years since 2012.
[tex]23,000*1.02^{x} =y[/tex]
