Question 751662
{{{ .8*30 = 24 }}} pints of antifreeze in 80% solution
Let {{{ w }}} = pints of water to be added 
to make solution 60% antifreeze
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{{{ 24 / ( 30 + w ) = .6 }}}
{{{ 24 = .6*( 30 + w ) }}}
{{{ 24 = 18 + .6w }}}
{{{ .6w = 6 }}}
{{{ w = 10 }}}
10 pints of waters needs to be added
check:
{{{ 24 / ( 30 + w ) = .6 }}}
{{{ 24 / ( 30 + 10 ) = .6 }}}
{{{ 24 / 40 = .6 }}}
{{{ 24 = .6*40 }}}
{{{ 24 = 24 }}}
OK