|A) 2/3 hrs||B) 3/4 hrs|
|C) 1/3 hrs||D) 1/4 hrs|
Walking at 3/4th of usual rate implies that time taken would be 4/3th of the usual time. In other words, the time taken is 1/3rd more than his usual time
so 1/3rd of the usual time = 15min
or usual time = 3 x 15 = 45min = 45/60 hrs = 3/4 hrs.