I'm looking to identify people who haven't been in attendance for X number of times.

I have a simple table with last names in A and first names in B. Row 1 has dates listed by mm/dd.

When someone is in attendance, I place in "x" in that cell.

What I would like is to track who has missed the last three times. In other words I need something that can search the table beginning with the correct/current date column, count back three columns and make a list of every name that has no "x" in any of the three cells.

Is this possible? Would there be a better way to track attendance that would allow such a function?