Answer
$m \angle D = 127^{\circ}$
Work Step by Step
The diagram is that of a parallelogram.
Opposite angles of a parallelogram are congruent. We see that $\angle D$ and $\angle B$ are opposite angles.
Let's set $m \angle D$ and $m \angle B$ equal to one another:
$m \angle D = m \angle B$
Let's plug in what we know:
$m \angle D = 127^{\circ}$