The triangle sum theorem states that the sum of measure of all the interior angles in a triangle equals 180; in this case, the fact that both lines are parallel has little significance to this particular problem.
\(m\angle 7+63+61=180\) | This is based on the triangle sum theorem mentioned above. Now, solve for the remaining unknown angle. |
\(m\angle 7+124=180\) | |
\(m\angle 7=56^{\circ}\) | |