M completes a task in 20 days and N completes the same task in 30 days. In how many days will both of them complete the same task working together?

Correct option is C

Given:
M's time to complete the task = 20 days
N's time to complete the task = 30 days
Solution:
LCM of (20, 30) = 60 units of work
Now, M's work rate = $$\frac{60}{20}$$​= 3 units/day
N's work rate = $$\frac{60}{30}$$​ = 2 units/day
Together, M and N's work rate = 3 + 2 = 5 units/day
The total time taken to complete 60 units of work together is:
Time = $$\frac{60}{5}$$​= 12 days
Thus, M and N will complete the task together in 12 days