Question 984793
A piece of work can be completed by 45 workers in 10 days
1 worker would take {{{ 45*10 = 450 }}} days to do the work
The rate of working for 1 worker is:
[ 1 job ] / [ 450 days ]
The fraction of the job that gets done in 4 days is:
{{{ 45*( 1/450 )*4 = .4 }}}
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That leaves {{{ 1 - .4 = .6 }}} as a
fraction of the job that is left
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There are {{{ 45 - 15 = 30 }}} workers left
Let {{{ d }}} = days for the remaining work to be finished
[ rate ] = [ rate ]
{{{ 30*( 1/450 ) = .6 / d }}}
{{{ 1/15 = 6/10d }}}
{{{ d = ( 6/10 )*15 }}}
{{{ d = 90/10 }}}
{{{ d = 9 }}}
The remaining workers will take 9 days 
to complete the work
Hope I got it!