A and B together do a job in 12 days. A alone takes 18 days. How long does B take alone?
A
36 days
B
30 days
C
28 days
D
24 days
Correct Answer: Option A — 36 days
Explanation:
B's rate = 1/12 - 1/18 = 3/36 - 2/36 = 1/36. B alone takes 36 days. This work problem requires subtracting individual rates from combined rates. Mastery of work-rate subtraction is essential as such problems appear in almost every competitive exam quantitative aptitude section often in more complex multi-worker forms.