In this question, the interest rate is 0.018% and you need to have $9.99 interest. That mean, you need to divide the target interest value with the interest rate. The calculation would be:
interest = bank account * interest rate
$9.99 = bank account * 0.018%
bank account = $9.99/ 0.018% (don't forget the % mean 1/100)
bank account = $55,500
Assuming that the $9.99 value is $9.9999... then the answer would be $55,555