Let the work be LCM of (9 and 12)=36 units. Let the amount of work done in one day with their normal efficiencies by A and B be x and y units respectively. Therefore, (x+y)×12=36 Or x+y=3...(1) Similarly, (x/2+3y)×9=36 Or x/2+3y=4...(2) Solving (1) and (2) for x, we get x=2 units Hence, A alone would take 36/x=36/2=18 days to complete the work with her normal efficiency.