(b) $9 \%$ of what is $13.5 ?$

Step 1 ：Translate the problem into an equation: \(0.09 * x = 13.5\)

Step 2 ：Divide both sides of the equation by 0.09 to solve for x: \(x = \frac{13.5}{0.09}\)

Step 3 ：Calculate the value of x: \(x = 150.0\)

Step 4 ：Final Answer: \(\boxed{150}\)