Time and work:
method: Fraction Technique
method: Fraction Technique
A = 10 days i.e so work done in a day is 1/10^{th}.
2^{nd} Method: Efficiency Technique
Work done by a person in unit time is defined as efficiency in Time and Work Problems
A = 10 days so efficiency of A per day = 100/10 = 10%
 Work from Days:
If A can do a piece of work in n days, then A's 1 day's work = 1 . n  Days from Work:
If A's 1 day's work = 1 , then A can finish the work in n days. n  Ratio:If A is thrice as good a workman as B, then:Ratio of work done by A and B = 3 : 1.Ratio of times taken by A and B to finish a work = 1 :3
2.  A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With help of C, they did the job in 4 days only. Then, C alone can do the job in:  

See below
Time and work part1