Question 1024870
20 men can make 112 meter wall in 6 days

The total labor was 6*20 or 120 man-days. 

So {{{(112meter/(120(man-day)))}}}

and reduces to {{{(14meter/(15(man-day)))}}}

{{{(14meter/(15(man-day)))(75man-days)}}} = 70 meters of wall. 

Note - 25 men working 3 days is simply 75 man-days