Question 789316
Let {{{ w }}} = kg of water to be evaporated
{{{ .15*60 = 9 }}} kg of salt in 15% solution
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{{{ 9 / ( 60 - w ) = .4 }}}
{{{ 9 = .4*( 60 - w ) }}}
{{{ 9 = 24 - .4w }}}
{{{ .4w = 24 - 9 }}}
{{{ .4w = 15 }}}
{{{ w = 37.5 }}}
37.5 kg of water must be evaporated
check:
{{{ 9 / ( 60 - w ) = .4 }}}
{{{ 9 / ( 60 - 37.5 ) = .4 }}}
{{{ 9 / 22.5 = .4 }}}
{{{ 9 = .4*22.5 }}}
{{{ 9 = 9 }}}
OK