Find a whole number percent that is equivalent to 12/30

To find the percent that is equivalent to $\frac{12}{30}$, we divide 12 by 30 and multiply by 100. Performing the calculations, we have $\frac{12}{30} \times 100 = 0.4 \times 100 = 40$. Therefore, $\frac{12}{30}$ is equivalent to $\boxed{40\%}$.