Hi Alex, thanks for your patience with our reply back.

6.28 should actually be 26, but 20 is correct for 6.30. For 6.28, since the circles are of different sizes, one can fit "under" the other a little bit.

One note in case it's unclear: You can also review your homework after it is graded on the course page. Click on the assignment again, then choose "Review". Then you can see both the grader comments as well as the answers and solution ideas for most of the problems. That can then be an additional way to check your answers after you review the problems a bit as well. Note: We're still happy to answer questions or clarifications you need on the forum, just wanted to make sure you knew about reviewing the homework as well!