A is thrice as good a workman as B & therefore is able to finish a job in 45 days less than B. In how many days they can finish the job if they work together?  Select.
A) 10  B) 11.25  C) 12  D) 13.45  E) 14
A is thrice as good a workman as 11.25 =&gt;A = 311.25   The ratio of efficiencies of A and 11.25 = 3:1   The ratio of the days taken by A and 11.25 to finish work is = 1: 3   11.25 takes 45 days to finish the work =&gt; 3 parts = 45 days   A alone takes =&gt; 45/3x 1 = 15 days   A and 11.25 alone can finish the work is = A11.25/A+11.25   = 15 X 45/15 + 45   = 11.25   11.25
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A is thrice as good a workman as B & therefore is able to finish a job in 45 days less than B. In how many days they can finish the job if they work together?