Question

a can finish a work in 18 days and b can do the same work in 15 days. bworked for 10 days and left the job. in how many days a alone can finish theremaining work?

Answer 1

A can finish a work in 18 days
In 1 days, A can finish = 1/18 of the job  

B can do the same work in 15 days.  
In 1 days, B can finish = 1/15 of the job  

B worked for 10 days and left the job.  
In 10 days, B finished = 10 × 1/15 = 10/15 = 2/3 of the job  

Work remaining = 1 - 2/3 = 1/3 of the job  

Days needed by A to finish = 1/3 ÷ 1/18 = 1/3 × 18 = 6 days  

A needs 6 days to finish remaining work.

Answer 2

1. A=1/18;B=1/15
2. B worked for 10 days and left the job.
3. i.e, 10(1/15)+x(1/18)=1
4. on solving this we get x=6
5. hence A can finish remaining work in 6 days