Smith and Ajit can complete a task in 12 days and 18 days, respectively. If they work together on the task for 4 days, then the fraction of the task that will be left is:

$\frac{4}{9}$

Smith = 12 days, Ajit = 18 days,

⇒ They both worked for 4 days together = (3 + 2) x 4 = 5 x 4 = 20 units,  ..(Efficiency × Days = Total work)

⇒ Remaining work = 36 - 20 = 16 units,

⇒ Fraction of work left = \(\frac{16}{36}\) = \(\frac{4}{9}\)