Question 725315
Let {{{ w }}} = liters of water to be added
{{{ .3*1000 = 300 }}} liters of antifreeze in the coolant
The amount of antifreeze does not change in this problem
{{{ 300 / ( 1000 + w ) = .25 }}}
{{{ 300 = .25*( 1000 + w ) }}}
{{{ 300 = 250 + .25w }}}
{{{ .25w = 50 }}}
{{{ w = 200 }}}
200 liters of water should be added
{{{ 300 / ( 1000 + w ) = .25 }}}
{{{ 300 / ( 1000 + 200 ) = .25 }}} 
{{{ 300 / 1200 = .25 }}}
{{{ .25 = .25 }}}
OK