Question

A can do a piece of work in 10 days and B in 12 days.

With the help of C they can finish the work in 4 days. How
long will C take to do it alone?
a) 12 days b) 15 days c) 18 days d) 20 days​

Answer 1

B. 15 days

Explanation:

A=10=1/10 of the job

B=12=1/12 of the job

A+B+C=4=1/4 of the job

A+B

=1/10 + 1/12

=10+12/120

=22/120

=11/60

(A+B+C) - (A+B)

=1/4 - 11/60

=5 - 11/60

=4/60

=1/15

It would take C alone 15 days to finish the job