Question 1148631
.
<pre>

8350 + 8350*r*6 = 12859    dollars


8350*6*r        = 12859 - 8350


8350*6*r        = 4509


r               = {{{4509/(8350*6)}}} = 0.09.


<U>ANSWER</U>.  Simple interest rate is 9% per annum.
</pre>

Solved.