A is twice as good a workman as B and together they finish a piece of work in 14 days. The number of days that A alone will take to finish the work is:

21

Total work = Efficiency × Time

                         A    :    B

Efficiency            2    :    1

Total work = 14 ( 2 + 1 )

= 42

Time taken by A alone to complete the work = \(\frac{ 42 }{ 2 }\)

= 21

The correct answer is Option (2) → 21