Practice Test 6

Lines $a$ and $b$ are parallel. A transversal intersects them, forming alternate interior angles $\angle 3$ (on line $a$) and $\angle 6$ (on line $b$). If $m\angle 3=112^\circ$, which statement correctly determines $m\angle 6$ and why?

In triangle $RST$, $m\angle R = 45^\circ$ and $m\angle S = 62^\circ$. A student wants to find $m\angle T$ and justify the method. Which choice gives a correct justification?