A can finish a piece of work in 36 days and B in 72 days. They begin the work together, but A leaves 6 days before the completion of the work. In how many total days the complete work will be done?

Correct option is D

Given:
Time taken by A = 36 days
Time taken by B = 72 days
A leaves 6 days before the completion of the work.
Formula Used:
Work Done = Rate of Work × Time
Solution:
Let the total number of days taken to complete the work be x.
Since A leaves 6 days before completion, A works for (x - 6) days.
B works for the entire duration of x days.
Formulate the work equation:
​$$\frac{x - 6}{36} + \frac{x}{72} = 1$$​​
2(x - 6) + x = 72
2x - 12 + x = 72
3x = 84
x = 28
The complete work will be done in 28 days.
Final Answer
So the correct answer is (d)