The distance between Chandigarh and Amritsar is 500 kms. A train starts from Chandigarh to Amritsar on Monday. In the midst of the journey, a technical glitch forces the driver to reduce the speed of the train by 20%. Had the glitch occurred 40 kms later, the train would have reached Amritsar 7 mins and 30 seconds earlier. Find the original speed of the train (before the glitch).