16. Exemplar example problems III

A train travels at a certain average speed for a distance of \(63 \ km\) and then travels a distance of \(72 \ km\) at an average speed of \(6 \ km/h\) more than its original speed. If it takes \(3\) hours to complete the total journey, what is its original average speed?

 

 

The original average speed of the train is \(km/h\).