Question 954362
Let {{{ x }}} = in3 of 45% dark chocolate needed
{{{ .45x }}} = in3 of dark chocolate in 45% mix
{{{ .2*18 = 3.6 }}} in3 of dark chocolate in 20% mix
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{{{ ( .45x + 3.6 ) / ( x + 18 ) = .3 }}}
{{{ .45x + 3.6 = .3*( x + 18 ) }}}
{{{ .45x + 3.6 = .3x + 5.4 }}}
{{{ .15x = 1.8 }}}
{{{ x = 12 }}}
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12 in3 of the 45% dark chocolate are needed