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:

Answer: Option D

(Smith + Ajit) × 4 = 4 × 5 = 20
Remaining work = 36 - 20 = 16
Then the fraction of the task that will be left is $$=\frac{16}{36}=\frac{4}{9}$$