Question 715199
Let {{{ w }}} = liters of water to be removed
{{{ .2*30 = 6 }}} liters of salt in 20% solution
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{{{ 6 / ( 30 - w ) = .5 }}}
{{{ 6 = .5*( 30 - w ) }}}
{{{ 6 = 15 - .5w }}}
{{{ .5w = 15 - 6 }}}
{{{ .5w = 9 }}}
{{{ w= 18 }}}
18 liters of water should be removed