Question

A certain work can be done in a certain time by 36 men but had there had been.9 more men it could have been done in 5 days less in how many days can 20 men do the same work

Answer 1

suppose total number of men = x 

x men can work a job in 60 days 
x men can work 1/60 job in 1 day 
1 man can work 1/60x in 1 day..........................1 

x+8 can do the same job in 50 days 
similarly, 
1 man can do 1/50(x+8) job in 1 day ..............2 

from 1 and 2, 1/60x = 1/50(x+8) 

solving the equation, x = 40 men.

Answer 2

Answer:

45

Step-by-step explanation:

Let unknown day be x

work done(W) by 36M= 1/x

W by 1 M =1/36x ---------(1)

9 more men =36 +9=45

similarly,

W by 45M = 1/(x-5)

W by 1M = 1/45×(x-5) --------(2)

(1)=(2)

1/36x=1/(45x-225)

x=9/225

from (1)

20M= 20/36x=5/9x

simplifying x

20M= 1/45

so 45 days