(e) $18 \%$ of what is 9 ?

Step 1 ：We need to find a number such that 18% of it is equal to 9. This can be represented by the equation \(0.18 * x = 9\), where x is the number we are trying to find.

Step 2 ：We can solve for x by dividing both sides of the equation by 0.18.

Step 3 ：So, the final answer is \(\boxed{50}\).