Your code works perfectly. However, it probably does not do what you intended.

  <?php
  // you defined $x as a _string_.
  // "rand int(1,20)" <-- not a function. 
  // just a sentence.
  $x = 'rand int(1,20)';

  // here, you cast the string to an integer
  // (because you're comparing it to an integer).
  // 'rand ...' equates to (0).
  if ($x <= 9 ){
      // therefore, 
      // the comparison is always TRUE
      echo "<p>congrats";
  }elseif($x >= 10 ){

      // and never FALSE.
      echo "you lose";
  }

You probably meant to do this:

  <?php
      // no quotes or "int"
      $x = rand( 1,20 );

The rest of your code should work as expected after that.

(Though you don't need the elseif; you could use just else and get the same result.)

no prob : )