Lines a and b are intersected by a transversal at points P and Q. On one side of the transversal, the interior angle at P measures (3x+15)∘ and the interior angle at Q measures (5x−35)∘.
a. (i) Find the value of x if the two interior angles are supplementary.
b. (ii) Calculate the measure of each interior angle.
c. (iii) Using your calculation, decide whether lines a and b are parallel. Give a reason for your answer.