Question 832410
Let {{{ x }}} = gallons of ethanol to be added
{{{ .02*1 = .02 }}} gallons of ethanol originally
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{{{ ( x + .02 ) / ( 1 + x ) = .1 }}}
{{{ x + .02 = .1*( 1 + x ) }}}
{{{ x + .02 = .1 + .1x }}}
{{{ .9x = .08 }}}
{{{ x = .08/.9 }}}
{{{ x = .0889 }}}
.0889 gallons of ethanol must be added
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check:
{{{ ( x + .02 ) / ( 1 + x ) = .1 }}}
{{{ ( .0889 + .02 ) / ( 1 + .0889 ) = .1 }}}
{{{ .1089 / 1.0889 = .1 }}}
{{{ .1089 = .1*1.0889 }}}
{{{ .1089 = .1089 }}}
OK