Question 683803
The liters of antifreeze in the radiator is
{{{ .6*25 = 15 }}} liters
Let {{{ x }}} = the number of liters to be drained and replaced with water
{{{ .6x }}} = liters of antifreeze in the mixture that is drained
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The key is that you end up with the same liters you started with
{{{ ( 15 - .6x ) / 25 = .4 }}}
{{{ 15 - .6x = .4*25 }}}
{{{ 15 - .6x = 10 }}}
{{{ .6x = 15 - 10 }}}
{{{ .6x = 5 }}}
{{{ x = 8.333 }}} liters
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check answer:
{{{ ( 15 - .6x ) / 25 = .4 }}}
{{{ ( 15 - .6*8.333 ) / 25 = .4 }}}
{{{ ( 15 - 5 ) / 25 = .4 }}}
{{{ 10/25 = .4 }}}
{{{ 10 = 10 }}}
OK