A car moves with a speed of 50 km/hr in the straight line and returns with the speed of 40 km/hr. find out average speed . I wrote the answer like this. Why am I wrong? Plz give reason and show the right way to do.

Dear Student,The car covers the same distance in it's to and fro journey.So we cannot take d1=50km and d2=40kmhere, d1=d2Let  x be the distance travelled by the car in straight line.Time taken to cover x km with a speed of 50km/h is,t1=distancespeed=x50hrWhen the car returns, it  again covers x km with a speed of 40km/h .Thus,t2=x40hrWe know,Average speed =total distancetotal timeAverage speed =x+xt1+t2=2xx50+x40=2x4x+5x200=200×2x9x=4009=44.44km/hRegards

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