An airplane flew for 6 hours with a tail wind of 60 km/hs. the return flight again dig the same wind took 8 hours. find the speed of the plain in still air.

let speed of plane = x

d = (x+60)6

d = (x-60)8

=> 6x + 360 = 8x - 480

=> 2x = 840

=> x = 420 km/hr