Teacher: 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'.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Problem: walking at 5 / 6 th of its usual speed a cab is 15 mnts late . find its usual time to cover the journey ? 
Options: a ) 25 m , b ) 45 m , c ) 32 m , d ) 75 m , e ) 62 m
Solution: d
Reason: New speed = 5 / 6 th of usual speed new time = 6 / 5 th of usual time 6 / 5 ut - ut = 15 m ut / 5 = 15 m ut = 75 m answer is d

Now, solve this instance: Problem: a contractor undertakes to built a walls in 50 days . he employs 70 peoples for the same . however after 25 days he finds that only 40 % of the work is complete . how many more man need to be employed to complete the work in time ? 
Options: a ) 105 , b ) 30 , c ) 35 , d ) 20 , e ) none of these
Student:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
a