If two parallel lines are intersected by a transversal, then interior angles on the same side of the transversal are .

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If a transversal intersects a pair of lines in such a way that a pair of alternate angles are equal, then the lines are _____.

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If a transversal intersects a pair of lines in such a way that the sum of interior angles on the same side of transversal is ${180}^{°}$, then the lines are _____.

In the following figure, $AB\left|\right|CD\left|\right|EF$  and $GH \Vert KL$. Find $\angle HKL$

In the following figure, show that $AB \Vert EF$

In the following figure, $PQ \Vert AB$ and $PR \Vert BC$. If $\angle QPR=102°,$ determine $\angle ABC$. Give reasons.