Lines g and h are parallel. A transversal k intersects them at points R and S. On the right side of k, the consecutive interior angles at R and S measure (4z+15)∘ and (2z+45)∘ respectively.
a. (i) State the relationship between these two consecutive interior angles.
b. (ii) Using the relationship, find the value of z.
c. (iii) Calculate the measure of the exterior angle at R on the right of the transversal.