Walking (6/7)th of his usual speed, a man is 12 minutes too late.
The usual time taken by him to cover that distance is:
New speed = (6/7) of usual speed.
New time = (7/6) of usual time.
Therefore (7/6 of usual time)- (usual time) = (1/5) hr.
=> (1/6 of usual time)= (1/5) hr
=> usual time = (6/5) hr
= 1 hr 12 min.