Question 949418
 five people working 8 hours a day can cut drain in 6 days.
find how many man-hrs required to do the task
5 * 8 * 6 = 240 man-hrs
:
 how many days will four people working 6 hours a day require for the same task
let d = no. of days required by 4 men working 6 hrs a day.
4 * 6 * d = 240 
24d = 240
d = 240/24
d = 10 days with 4 men working 6 hrs a day
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:
See if that checks out 4 * 6 * 10 = 240 man-hrs