Question 719853
At the start {{{ 30 }}} ounces are gold and
{{{ 120 }}} ounces are silver
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You are not changing the ounces of gold
only the ounces of silver
Let {{{ s }}} = ounces of silver to be added
{{{  30 / ( 150 + s ) = .05 }}}
{{{ 30 = .05*( 150 + s ) }}}
{{{ 30 = 7.5 + .05s }}}
{{{ .05s = 22.5 }}}
{{{ s = 22.5 / .05 }}}
{{{ s = 450 }}}
450 ounces of silver must be added
check:
{{{  30 / ( 150 + s ) = .05 }}}
{{{  30 / ( 150 + 450 ) = .05 }}}
{{{ 30 / 600 = .05 }}}
{{{ 30 = .05*600 }}}
{{{ 30 = 30 }}}
OK