Question 574952
{{{ .55*17 = 9.35 }}} quarts of antifreeze in 55% solution
{{{ 17 - 9.35 = 7.65 }}} quarts of water in 55% solution
Let {{{ x }}} = quarts of water to be evaporated
given:
{{{ 9.35 / ( 17 - x )  = .85 }}}
{{{ 9.35 = .85*( 17 - x ) }}}
{{{ 9.35 = 14.45 - .85x }}}
{{{ .85x = 14.45 - 9.35 }}}
{{{ .85x = 5.1 }}}
{{{ x = 5.1/.85 }}}
{{{ x = 6 }}}
6 quarts of water should be evaporated
check:
{{{ 7.65 - 6 = 1.65 }}} quarts of water left
{{{ 1 - .85 = .15 }}}
{{{ 1.65 / ( 17 - 6 ) = 1.65/11 }}}
{{{ 1.65/11 = .15 }}}
The water left is 15% of the solution 
OK