Question 854166
Let {{{ x }}} = fraction of stock
neither owned by Alberto nor Renetta
{{{ 5/9 }}} = Alberto's fraction
{{{ (5/9)*(1/2) = 5/18 }}} = Renetta's fraction
{{{ 5/9 + 5/18 + x = 1 }}}
{{{ 10/18 + 5/18 + x = 1 }}}
{{{ x = 1 - 15/18 }}}
{{{ x = 3/18 }}}
{{{ x = 1/6 }}}
1/6 of the stock is neither owned 
by Alberto nor Renetta