Correct Answer - Option 1 : 60 days
Given
A and B can complete the work = 15 days
B can complete the work = 20 days
Formula Used
Work = Time × Efficiency
Calculation
LCM of (15, 20) = 60
Let total work be 60
Efficiency of A and B together = 60/15 = 4/days
Efficiency of B = 60/20 = 3/days
So, Efficiency of A = 4 - 3 = 1/day
Time taken by A to complete the work alone = 60/1 = 60 days
∴ The required answer is 60 days.
