Question

Two planes start from a city and fly in opposite directions, one averaging a speed of 40 km/h more than that of the other. If they are 3400km apart after 5 hours, find their average speeds.

Answer 1

Let the average speed of the ait plane = x km/hr.
Then, the average speed of the other airplane = (x + 40)km/hr
As the planes are moving in opposite directions we will add the average speed of the plane to get the total speed = x + x + 40 = (2x + 40) km/hr
Distance between the airplanes = 3400km.
After 5 hours they are 3400km apart

∴ 5 = `(3400)/(2x + 40)`

⇒ 10x + 200 = 3400
⇒ 10x - 3200
⇒ x = 320lm/hr
Therefore, the average speed of the plane = 320km/hr
And average speed of the other plane = (320 + 40) = 360km/hr.