Asghar traveled from his house to his office at 10 km/hr and returned at rate of 9 km/hr. Rohit travelled through the same path both ways at 12 km/hr and took 10 minutes less than Asghar. What is the distance between Asghar’s house and his office?

A. 3000m
B. 7500m
C. 3750m
D. 7000m

Average speed for Raj is: v = (2*9*10)/(9+10) = 180/19 km/hr = 50/19 m/s
Average speed for Rohit = 12 km/hr = 10/3 m/s
Now, v = d/t
As d is same, v*t = constant.
Let, t be the time taken by Rohit in seconds. Hence, time taken by Raj is (t +600)s
50/19 * (t + 600) = 10/3 * t
150*(t + 600) = 190t
t = 2250s
Let d be the distance between the house and the office
2d = 2250 * 10/3
2d = 7500 m
d = 3750m