Jessica has an account with a credit union. Her account earns 2.4% simple interest yearly. Exactly a year and a half ago, she opened her account with $900. How much interest has she earned so far?

The formula for calculating simple interest is:

Interest = Principal x Rate x Time

In this case, the principal is $900, the rate is 2.4%, and the time is 1.5 years (since it has been a year and a half).

So, plugging in the values:

Interest = $900 x 0.024 x 1.5
Interest = $900 x 0.036
Interest = $32.40

Therefore, Jessica has earned $32.40 in interest so far.