In a reverted gear train, two gears P and Q are meshing, Q-R is a compound gear, and R and S are meshing. The modules of P and R are 4 mm and 5 mm respectively. The numbers of teeth in P, Q and r are 20, 40 and 25 respectively. The number of teeth in S is
I got this question in examination.
Query is from Law of Gearing in portion Toothed Gearing & Gear Trains of Machine Kinematics