**A can do a piece of work in 20 days and B in 15 days. They worked together on it for 6 days … . How long will B take to finish the…**

###### Answers:

A can do a piece of work in = 20 days

B can do a piece of work in = 15 days

∴ A’s 1 day work = 1/20

B’s 1 day work = 1/15

(A + B)’s 1 day work = 1/20 + 1/1 5

= (3 + 4)/60 = 7/60

(A + B)’s 6 day work = (7/60) × 6 = 7/10

Remaining work = 1 – (7/10)

= (10 – 7)/10 = 3/10

B can do 1 work in = 15 days

B can do 3/10 work in = 15 × (3/10) days

= 45/10 days = 9/2 days = 4. ½ days