Correct Answer - C
(i) Tank was filled in 14 hours, i.e., pipe A worked for 14 hours.
(ii) Tank is filled in 14 hours.
(iii) Pipe A is opened for 14 hours and let pipe B is opened for x hours.
(iv) Frame the equatin and solve for x.
i.e.,`(14)/(12)-(x)/(18)=1`