PLEASEEEEE HELPPPPP

According to the given statement, $\triangle {\text{PQR}} \cong \triangle {\text{STU}}$. Corresponding angles of congruent triangles have equal measure. Therefore, since $m \angle \text{S} = 78^{\circ}$, this means that $m \angle \text{P} = 78^{\circ}$. By the widely known Triangle Sum Angle Theorem, the sum of the interior angles of the triangle equals 180 degrees.

$m \angle {\text{P}} + m \angle {\text{Q}} + m \angle {\text{R}} = 180^{\circ} \\ 78^{\circ} + m \angle {\text{Q}} + 80^{\circ} = 180^{\circ} \\ 158^{\circ} + m \angle {\text{Q}} = 180^{\circ} \\ m \angle {\text{Q}} = 22^{\circ}$