Question 788164
Let {{{ x }}} = ml of 10% solution to be added
{{{ .1x }}} = ml of juice in 10% solution
{{{ 10 }}} ml = ml of juice in 100% solution
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{{{ ( .1x + 10 ) / ( x + 10 ) = .4 }}}
{{{ .1x + 10 = .4*( x + 10 ) }}}
{{{ .1x + 10 = .4x + 4 }}}
{{{ .3x = 6 }}}
{{{ x = 20 }}}
20 ml of 10% solution needs to be added
check:
{{{ ( .1x + 10 ) / ( x + 10 ) = .4 }}}
{{{ ( .1*20 + 10 ) / ( 20 + 10 ) = .4 }}}
{{{ ( 2 + 10 ) / 30 = .4 }}}
{{{ 12 = .4*30 }}}
{{{ 12 = 12 }}}
OK