Question 715695
 {{{ (y-(9 / y)) / (1+(3 / y)) }}}
Multiply top and bottom by {{{ y }}}
{{{ ( y^2 - 9 ) / ( y + 3 ) }}}
Factor
{{{ ( (y + 3)*(y - 3) ) / ( y + 3 ) }}}
{{{ y - 3 }}} answer
Note that {{{ y }}} cannot be {{{ 0 }}}, since
that would make the denominator 
equal to infinity