Speed problem in quadratic equation

In a flight of 600km, a aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200km/hr and the time of flight increased by 30 minutes. Find the duration of flight. (Ans : 1 hr)

Concept: Speed problem

Formula: S = V x t , where S = distance, V = speed, t = time

Difference in speed = normal speed – changed speed