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.