John covers a part of the journey at 20kmhr and the remaining at 70kmhr, taking total of 8 hours to cover the distance of 400 km. How many hours he has been driving at 70kmhr?

John covers a part of the journey at 20kmhr and the remaining at 70kmh

1.	John covers a part of the journey at 20kmhr and the remaining at 70kmhr, taking total of 8 hours to cover the distance of 400 km. How many hours he has been driving at 70kmhr?
Answer» John covers a part of the journey at $20 \frac{k m}{h r}$ and the remaining at $70 \frac{k m}{h r}$ , taking total of 8 hours to cover the distance of 400 km. How many hours he has been driving at $70 \frac{k m}{h r}$ ?