Question 700345
Let {{{ x }}} = gallons of skim milk needed
{{{ .05*80 = 4 }}} gallons of butterfat in 5% milk
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{{{ 4 / ( 80 + x) = .02 }}}
{{{ 4 = .02*( 80 + x ) }}}
{{{ 4 = 1.6 + .02x }}}
{{{ .02x = 4 - 1.6 }}}
{{{ .02x = 2.4 }}}
{{{ x = 120 }}}
120 gallons of skim milk must be added
check:
{{{ 4 / ( 80 + x) = .02 }}}
{{{ 4 / ( 80 + 120) = .02 }}}
{{{ 4 / 200 = .02 }}}
{{{ 4 = 4 }}}
OK