Shailay Watson asks:

1. “On a 120 km track, a train moves the first 30 km at a uniform speed of 30 km/h. How fast must the train in the next 90 km so as to have average speed 60 km/h for the entire trip?”
2. “A person goes form one place to another on bike
   with uniform speed 40 km/h and returns back at
   uniform speed of 60 km/h. Find average speed
   during the journey.”