Question

8. A and B can do a piece of work in 20 days and 30 days respectively. B started the work and after 5 days A joined. Find the total time taken to complete the work.​

Answer 1

Answer:

A's one-day work =1/30

B's one-day work = 1/20

A+B ‘s one-day = 1/30+1/20=2+3/60=5/60=1/12

So A and B work together and complete by 12 days

B leaves 5days before complete the work

So they worked together for 7 days

7*1/12=7/12

Total work = 1–7/12=5/12

Remaining work = 5/12

A finishes remaining work,

Full work in 30days

1= 30

5/12= x

x= (5/12)*30=150/12=12.5

So A takes 13 days to complete remaining work.

Total time to complete the work is 7+13= 20days