In a parallelogram, opposite angles are equal and consecutive angles are supplementary (they add up to 180 degrees).
Given:
- \( m\angle BCD = 115^\circ \)
To find \( m\angle CDE \) (which is the same as \( m\angle B \)), we use the property that consecutive angles are supplementary:
\[ m\angle BCD + m\angle CDE = 180^\circ \]
Substituting the known angle:
\[ 115^\circ + m\angle CDE = 180^\circ \]
Now, we can solve for \( m\angle CDE \):
\[ m\angle CDE = 180^\circ - 115^\circ \] \[ m\angle CDE = 65^\circ \]
Thus, the measure of angle \( CDE \) is:
\[ \boxed{65^\circ} \]