To find the commission rate, you can use the formula:
\[ \text{Commission Rate} = \left( \frac{\text{Commission Earned}}{\text{Total Sales}} \right) \times 100 \]
In this case, the commission earned is $150, and the total sales amount to $3,000.
Now plug in the values:
\[ \text{Commission Rate} = \left( \frac{150}{3000} \right) \times 100 \]
Calculating the fraction:
\[ \frac{150}{3000} = 0.05 \]
Now, multiplying by 100 to get the percentage:
\[ 0.05 \times 100 = 5% \]
So, the commission rate is 5%.