Indicating that certain cells are marked as "paid."
=IF(AND(ISBLANK(D27),
ISBLANK(I27),
ISBLANK(N27)),
"",
"pd")&","&
IF(AND(ISBLANK(D26),
ISBLANK(I26),
ISBLANK(N26)),
"",
"pd")&","&
IF(AND(ISBLANK(D24),
ISBLANK(I24),
ISBLANK(N24)),
"",
"pd")&","&
IF(AND(ISBLANK(D25),
ISBLANK(I25),
ISBLANK(N25)),
"",
"pd")