In triangle QPS and triangle QSR,
PQ = RQ [Given]
Angle PQS = Angle SQR [ a = a]
QS = QS [Common]
So, triangle QPS is congruent to triangle QSR by SAS (Side-Angle-Side) congruence rule.
So,
PS = SR [By CPCT (Corresponding parts of Congruent triangles) ]
=> b = 17
