Explanation:

- The total distance to cover is 260 km in 4 hours.

- First Leg: The driver covers a distance at 56 km/h for 75 minutes.

- Distance = Speed × Time = 56 km/h × (75/60) h = 70 km.

- Second Leg: The next 90 km is at 60 km/h.

- Time taken = Distance ÷ Speed = 90 km ÷ 60 km/h = 1.5 hours.

- Total Time for First and Second Leg:

- = (75/60) hours + 1.5 hours

- = 1.25 hours + 1.5 hours

- = 2.75 hours.

- Remaining Time:

- Total time allowed is 4 hours, so remaining time is 4 - 2.75 = 1.25 hours.

- Remaining Distance:

- Total distance is 260 km. He already covered 70 km + 90 km = 160 km.

- Remaining distance = 260 km - 160 km = 100 km.

- Required Speed for Remaining Distance:

- Speed = Distance ÷ Time = 100 km ÷ 1.25 hours = 80 km/h.

Correct Answer: Option 3 - 80 km/h

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