Question 815190
Let {{{ w }}} = gallons of distilled water needed
{{{ .3*50 = 15 }}} gallons of alcohol in 30% solution
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{{{ 15 / ( w + 50) = .25 }}}
{{{ 15 = .25*( w + 50 ) }}}
{{{ 15 = .25w + 12.5 }}}
{{{ .25w = 2.5 }}}
{{{ w = 2.5/.25 }}}
{{{ w = 10 }}}
10 gallons of water must be added
check:
{{{ 15 / ( w + 50) = .25 }}}
{{{ 15 / ( 10 + 50) = .25 }}}
{{{ 15 = .25*60 }}}
{{{ 15 = 15 }}}
OK