in his daily routine Mr.Jha comes in his car to pick up his wife after her office gets over. They reach home exactly at 6pm every day. One day Mrs jha`so office gets over one hour earlier than the scheduled time and hence she starts waking at the rate of 3km per hour towards home.mr jha meets his wife on the way to her office and they reach home at 5:45pm what is the speed of Mr jha`s car and how long did Mrs jha walk

Question implies that Mrs Jha got picked up 7.5 mint. Early than any other day, means if on any other day she use to get car at 5 o'clock, on that she got the car at 4:52.5 and as she started walking earlier by one hour There fore she walked for 52.5 mint.

I ma not sure .. pls have a look at it .. they reached 15 min early means car was driven for 7.5 min less den what it is driven daily. It shows lady travelled for 52.5 min and distacnce covered by her in 52.5 min = distance by car in 7.5 min so ratio of speed is 1:7 hence speed of car is 21kmph. and lady traveled for 52.5 km.