Question 1099061
Let {{{ x }}} = mL of pure alcohol needed
{{{ .05*60 = 3 }}} mL of alcohol in the 5% mixture
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{{{ ( x + 3 ) / ( x + 60 ) = .8 }}}
{{{ x + 3 = .8*( x + 60 ) }}}
{{{ x + 3 = .8x + 48 }}}
{{{ .2x = 45 }}}
{{{ x = 225 }}}
225 mL of pure alcohol should be added
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check answer:
{{{ ( x + 3 ) / ( x + 60 ) = .8 }}}
{{{ ( 225 + 3 ) / ( 225 + 60 ) = .8 }}}
{{{ 228 / 285 = .8 }}}
{{{ 228 = .8*285 }}}
{{{ 228 = 228 }}}
OK