RRB Group D 20-Sep-2018 Shift 3 Solved Paper

A man has to cover a distance of 40 kms. He walks 16 kms at the speed of 4 km/hr and the rest is covered by Tonga. If he had covered 16 kms by Tonga and the rest by walking at the speed of 4 km/hr, then he would have taken 1 hour more. Find the speed of Tonga.