PHP, 40 Bytes
=============

    <?=bcdiv(($a=$argv)[1],$a[2],$a[3])[-1];

[bcdiv][1]

[Online Version][2]


  [1]: http://php.net/manual/en/function.bcdiv.php
  [2]: http://sandbox.onlinephpfunctions.com/code/bcba44f9eceb6971913dc22b05e8217c6ff4cd96