I need to correct this function to calculate the difference between two cells
which can end up as negative number. Bellow is a sample of the function:

What I have is this: =IF(I7<0.5,K$2-I7,0). Here cell K$2 = 12:00 P.M. and
cell I7 = 12:25 P.M. I need to be able to show both negative and or positive
numbers as the need arrises. If there are no value in either cell's, then,
show "" an empty string instead. Is this possible?