Question 1018650
{{{ .17*17 = 2.89 }}} = liters of salt in 17% solution
Let {{{ x }}} = liters of water to be evaporated from
17% solution
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Note that liters of salt in solution doesn't change
{{{ 2.89 / ( 17 - x ) = .25 }}}
{{{ 2.89 = .25*( 17 - x ) }}}
{{{ 2.89 = 4.25 - .25x }}}
{{{ .25x = 1.36 }}}
{{{ x = 5.44 }}}
5.44 liters of water needs to be evaporated
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check:
{{{ 2.89 / ( 17 - x ) = .25 }}}
{{{ 2.89 / ( 17 - 5.44 ) = .25 }}} 
{{{ 2.89 / 11.56 = .25 }}}
{{{ .25 = .25 }}}
OK