In triangle \( \triangle TUV \), it is given that \( \angle T \cong \angle V \) and \( m\angle U = 54^\circ \). Since \( \triangle TUV \) is isosceles with \( \angle T \) and \( \angle V \) as the equal angles, we can denote \( m\angle T = m\angle V = x \).
The sum of the angles in any triangle is \( 180^\circ \). Thus, we have:
\[ m\angle T + m\angle V + m\angle U = 180^\circ \]
Substituting in the known values:
\[ x + x + 54^\circ = 180^\circ \]
This simplifies to:
\[ 2x + 54^\circ = 180^\circ \]
Now, subtract \( 54^\circ \) from both sides:
\[ 2x = 126^\circ \]
Next, divide by 2:
\[ x = 63^\circ \]
So, \( m\angle T = 63^\circ \).
Therefore, the correct response is:
m∠T = 63°.