Question 261721
Gear A: 18 teeth -> 30 rev / min -> 60 rev / 2 min.
Gear B: 36 teeth 
Gear C: 9 teeth.
---
The LCM (18, 36, 9) = 36
9*4 = 36
4*30 = 120
--
So, gear C turns 120 revolutions / min.