Question 1094039
Let {{{ x }}} = gallons of 80% antifreeze needed
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{{{ ( .8x + .3*60 ) / ( x + 60 ) = .7 }}}
{{{ ( .8x + 18 ) / ( x + 60 ) = .7 }}}
{{{ .8x + 18 = .7*( x + 60 ) }}}
{{{ .8x + 18 = .7x + 42 }}}
{{{ .1x = 24 }}}
{{{ x = 240 }}}
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240 gallons of 80% solution are needed
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check:
{{{ ( .8*240 + .3*60 ) / ( 240 + 60 ) = .7 }}}
{{{ ( 192 + 18 ) / 300 = .7 }}}
{{{ 210 = .7*300 }}}
{{{ 210 = 210 }}}
OK