In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: a can complete a work in 12 days and b can do the same work in 8 days . if a after doing 2 days , leaves the work , find in how many days b will do the remaining work ? 
Options: a ) 2 days , b ) 4 1 / 2 days , c ) 6 1 / 2 days , d ) 7 3 / 4 days , e ) 10 days
c

Problem: car a runs at the speed of 70 km / hr & reaches its destination in 10 hr . car b runs at the speed of 35 km / h & reaches its destination in 10 h . what is the respective ratio of distances covered by car a & car b ? 
Options: a ) 11 : 5 , b ) 11 : 8 , c ) 13 : 7 , d ) 15 : 7 , e ) 2 : 1
e

Problem: a train is moving at 6 / 7 of its usual speed . the train is 30 minutes too late . what is the usual time for the train to complete the journey ? 
Options: a ) 1 hour , b ) 30 minutes , c ) 3 hours , d ) 2 hours 30 min , e ) 2 hours

c