A and B can do a piece of work in 12 days, B and C in 15 days, and C and A in 20 days. How many days will A, B, and C together take to finish the work?

by

A. 20 days
B. 17 days
C. All of these
D. 10 days

🧠 Explanation (Math):

Given: $A+B=12$, $B+C=15$, $C+A=20$ days
Step 1: Pair rates $=1/12+1/15+1/20=(5+4+3)/60=1/5$.
Step 2: Sum individual rates $=(1/5)/2=1/10$.
Step 3: Together time $=1/(1/10)=10$ days.
Final Answer: 10 days