Question 902646
Let {{{ x }}} = ounces of 11% solution needed
{{{ .11x }}} = ounces of salt in 11% solution
{{{ .2*4 = .8 }}} ounces of  salt in 20% solution
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{{{  ( .11x + .8 ) / ( x + 4 ) = .17 }}}
{{{ .11x + .8 = .17*( x + 4 ) }}}
{{{ .11x + .8 = .17x + .68 }}}
{{{ .06x = .12 }}}
{{{ x = 2 }}}
2 ounces of 11% solution are needed
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check:
{{{  ( .11x + .8 ) / ( x + 4 ) = .17 }}}
{{{  ( .11*2 + .8 ) / ( 2 + 4 ) = .17 }}}
{{{ ( .22 + .8 ) / 6 = .17 }}}
{{{ 1.02 = 6*.17 }}}
{{{ 1.02 = 1.02 }}}
OK