Question 954365
You probably mean "pints", not "points"
Let {{{ x }}} = pints of 10% LJM needed
{{{ .1x }}} = pints of LJ in 10% LJM
{{{ .6*20 = 12 }}} pints of LJ in 60% LJM
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{{{ ( .1x + 12 ) / ( x + 20 ) = .4 }}}
{{{ .1x + 12 = .4*( x + 20 ) }}}
{{{ .1x + 12 = .4x + 8 }}}
{{{ .3x = 4 }}}
{{{ x = 13.333 }}}
13 and 1/3 pints of 10% LJM must be added
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check:
{{{ ( .1x + 12 ) / ( x + 20 ) = .4 }}}
{{{ ( .1*13.333 + 12 ) / ( 13.333 + 20 ) = .4 }}}
{{{ ( 1.333 + 12 ) / 33.333 = .4 }}}
{{{ 13.333 / 33.333 = .4 }}}
{{{ .4 = .4 }}}
Hope I got it