The initial deposit is PV=$840.
The annual interest rate is r=2% not compounded.
The period we are evaluating is 6 month, or n=0.5 years.
As the interest is not compounded, we can calculate the interest I can be calculated as:
[tex]\begin{gathered} I=PV\cdot n\cdot r \\ I=840\cdot0.5\cdot0.02 \\ I=840\cdot0.01 \\ I=8.40 \end{gathered}[/tex]Answer: the interest is $8.40.