Mathematics

When two triangles are congruent in the same order, their corresponding angles are equal—so $\angle L = \angle P$, $\angle M = \angle Q$, and $\angle N = \angle R$. You have two equations from these angle pairs, but you also know that all angles in any triangle sum to $180°$. Use the angle sum property on one triangle to find $a$, then use a correspondence equation to find $b$.

When two triangles are congruent in the same order, their corresponding angles are equal—so $\angle L = \angle P$, $\angle M = \angle Q$, and $\angle N = \angle R$. You have two equations from these angle pairs, but you also know that all angles in any triangle sum to $180°$. Use the angle sum property on one triangle to find $a$, then use a correspondence equation to find $b$.