A student pilot was required to fly to an airport and then return as part of his flight training. Th

The distance going and the distance returning are the same, so call that distance d km. Time = distance ÷ speed, so the time going is d/120 hours and the time coming back is d/150 hours.

The two times add up to 3 hours: d/120 + d/150 = 3. The LCM of 120 and 150 is 600, so multiply everything by 600: 5d + 4d = 1800, which gives 9d = 1800, so d = 200.

So the two airports are 200 km apart. Check: 200 ÷ 120 = 1⅔ hours going, and 200 ÷ 150 = 1⅓ hours returning. 1⅔ + 1⅓ = 3 hours, which matches the question.