Aptitude and Reasoning

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 :       

A.  1 hour                                               

B.  1 hr 12 min

C.  1 hr 15 min                                      

D.  1 hr 20 min

The ratio between the speeds of two trains is 7:8, If the second train runs 400 kms in 4 hours, then the speed of the first train is :

A.  70 km/hr                                         

B.  75 km/hr

C.  84 km/hr                                          

D.  87.5 km/hr