Question

△def ≅ △stu. what is m∠u?

Explanation:

Step1: Recall property of congruent triangles

Corresponding angles of congruent triangles are equal. Since $\triangle DEF\cong\triangle STU$, $\angle U$ corresponds to $\angle E$.

Step2: Identify measure of $\angle E$

From $\triangle DEF$, we see that $m\angle E = 42^{\circ}$.

Answer:

$42$