Question 1053831
RT=J relates constant work rate, time, and quantity of jobs.  Your example refers mostly to 1 job.  If r is one-man work rate and there are n men working on the same job, the rate of this group is {{{n*r}}}.


Look at how much of the job is done every 10 days...


Basic plan for work was  {{{40*r*40=1}}} from which {{{r=1/1600}}}.


Now check each ten-day increment of work done.
-
{{{40(1/1600)*10}}}
{{{1/4}}}
-
{{{35(1/1600)*10}}}
{{{35/160}}}
{{{7/32}}}
-
{{{30(1/1600)*10}}}
{{{3/16}}}
-
{{{25(1/1600)*10}}}
{{{25/160}}}
{{{5/32}}}
-
What is the sum up to these end of 40 days?
{{{8/32+7/32+6/32+5/32}}}
{{{26/32}}}
Keep going...
-
{{{20(1/1600)*10}}}
{{{1/8}}}
-
{{{15(1/1600)*10}}}
{{{15/160}}}
{{{3/32}}}
-
{{{10(1/1600)*10}}}
{{{1/16}}}
-
{{{5(1/1600)*10}}}
{{{5/160}}}
{{{1/32}}}
-
What is the total sum of the job up to these 80 days?
{{{26/32+1/8+3/32+1/16+1/32}}}
{{{32/32}}}
{{{highlight(32/32=1)}}}
<b>THIS IS ALL OF THE 80 DAYS.</b>