Question

A man saves 180minutes in covering a certain distance when he increases his speed from 25km/hr to 30km/hr.find the ditance he travelled?

Answer 1

Let the distance be x km
Time taken to travel x  with speed 25kmph= x/25h
Time taken to travel x distance with 30kmph=x/30 h
As per question x/25=x/30 +180/60
                         ⇒ x/25=x/30 + 3
                         ⇒ (6x-5x)150=3
                         ⇒ x= 450km
Distance is 450km

Answer 2

let distance=x
and timetaken = y

speed=x1/y1=25km/hr
here x1=25y1

speed=30km/hr
here x2=30y2

y1-y2=3hr

therefore
450