11/21 or 9/17. which one is greater and what is the work/common denominaters

Answer 1

17 is a prime number so the LCD is 21*17 = 357

11/21 * 17/17 = 187/357

9/17 * 21/21 = 189/357

189 is bigger than 187

Answer 2

-79
-79 9/17