Question 1124800
Let {{{ x }}} = ml of pure alcohol needed
{{{ .6*385 = 231 }}} ml of alcohol in 60% mixture
————— 
{{{ ( x + 231 ) / ( x + 385 ) = .65 }}}
{{{ x + 231 = .65*( x + 385 ) }}}
{{{ x + 231 = .65x + 250.25 }}}
{{{ .35x = 19.25 }}}
{{{ x = 55 }}}
55 ml of pure alcohol are needed
Check:
{{{ ( 55 + 231 ) / ( 55 + 385 ) = .65 }}}
{{{ 286 / 440 = .65 }}}
{{{ .65 = .65 }}}
OK