Count; make sense (3,2)
I believe the answer is:
add up
I believe this is a double definition.
'count' is the first definition.
(adding up is a kind of counting)
'make sense' is the second definition.
(synonyms)
(Other definitions for add up that I've seen before include "Seem to be sensible" , "Total; make sense" , "Make sense; count" , "Aggregate, get total" , "Put together (numbers)" .)