To find the distance left to reach Bloomsfield after \( \frac{3}{12} \) hours of traveling, we first simplify the fraction \( \frac{3}{12} \) to \( \frac{1}{4} \) hours.
Next, we can substitute \( h = \frac{1}{4} \) into the function \( D(h) = 440 - 65h \):
\[ D\left(\frac{1}{4}\right) = 440 - 65\left(\frac{1}{4}\right) \]
Now, calculate \( 65 \times \frac{1}{4} \):
\[ 65 \times \frac{1}{4} = \frac{65}{4} = 16.25 \]
Now substitute that back into the distance function:
\[ D\left(\frac{1}{4}\right) = 440 - 16.25 = 423.75 \]
Thus, the distance left to get to Bloomsfield after \( \frac{3}{12} \) hours of traveling is \( \boxed{423.75} \) miles.