P.m. Find the total duration of the journey.answer is 78hours 30 minutes​

540 km journey takes 7 hours 30 minutes.

Two -Third of the journey = 2/3×540=360 km

Time taken =360/80=4 hours 30 minutes.

Remaining time =7−4=3 hours

Remaining Distance =540−360=180 km

Speed =180/3 =60 km/hr