How do I figure out 7-7/8 x 2-4/7?

I'm getting the answer 20-7/28. Not sure if I got to this answer right. I am converting 7-7/8 and 2-4/7 into improper fractions - I get 63/8 and 18/7, respectively. Then I solved 63/8 x 18/7 which came to 567/28 = 20-7/28. What am I doing wrong here???