Question 919789
Let {{{ n }}} = number of men employed first
{{{ (1/2) / 24 = 1 / 48 }}} = the rate of working
for {{{ n }}} men
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{{{ 1/ ( 48n ) }}} = the rate of working for {{{ 1 }}} man
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Then, 16 more men were employed and the 
remaining job was completed in 16 days
For {{{ 1 }}} man, this is a rate of:
{{{ (1/2) / (( n+16)*16 ) }}}
{{{ 1 / ( 2*16*( n + 16 ) ) }}}
{{{ 1 / ( 32n + 512 ) }}}
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Now I can say:
{{{ 1 / ( 48n ) = 1 / ( 32n + 512 ) }}}
{{{ 48n = 32n + 512 }}}
{{{ 16n = 512 }}}
{{{ n = 32 }}}
32 men were employed first
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check:
{{{ 1 / ( 48n ) = 1 / ( 32n + 512 ) }}}
{{{ 1 / ( 48*32 ) = 1 / ( 32^2 + 512 ) }}}
{{{ 1 / 1536 = 1 / ( 1024 + 512 ) }}}
{{{ 1 / 1536 = 1 / 1536 }}}
OK