Question 793786
Let {{{ x }}} = liters of $1.80 / liter OJ needed
{{{ 1.8x }}} = the cost of {{{  x }}} liters of $1.80 / liter OJ
{{{ 2.4*1.15 = 2.76 }}} = the cost of 2.4 liters of $1.15 / liter OJ
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{{{ ( 1.8x + 2.76 ) / ( x + 2.4 ) = 1.54 }}}
This is just saying:
( cost / liter ) = ( cost / liter )
{{{ 1.8x + 2.76 = 1.54*( x + 2.4 ) }}}
{{{ 1.8x + 2.76 = 1.54x + 3.696 }}}
{{{ 1.8x - 1.54x = 3.696 - 2.76 }}}
{{{ .26x = .936 }}}
{{{ x = 3.6 }}}
3.6 liters of $1.80 / liter OJ are needed
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check:
{{{ ( 1.8x + 2.76 ) / ( x + 2.4 ) = 1.54 }}}
{{{ ( 1.8*3.6 + 2.76 ) / ( 3.6 + 2.4 ) = 1.54 }}}
{{{ ( 6.48 + 2.76 ) / 6 = 1.54 }}}
{{{ 9.24 = 6*1.54 }}}
{{{ 9.24 = 9.24 }}}
OK