Concept:When two parallel lines are cut by a transversal, alternate interior angles are equal.Explanation:In the diagram, ∠QPR and ∠TSR are alternate interior angles because QP∥ST and the slanted line through P, R, and S acts as the transversal.Therefore, alternate angles are equal:∠TSR=∠QPR.Given:∠QPR=68∘.So:∠TSR=68∘.Hence, the required value of angle TSR is 68∘.Answer:68∘