How do I use isblank formula with the divide function?

I am trying to calculate a percentage of two columns and I know how to do that, but I do not want it to include the blank cell in the response. How do I go about that?

Currently, my formula looks like =DIVIDE(SUM(J:J),SUM(E:E))

Thank you

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google sheets – cant find a solution of ISBLANK function to work

How do I insert an ISBLANK function into this formula?
= (IF (D21-T21 <= S25, "TIMES", (D21-T21)))

if cell D is blank, cell E is blank, otherwise the above formula will be executed.
-also, I want this function to be present in all the cells of column E

Thank you

Column calculated with IF ISBLANK, if it is not "ABC", then returns "XYX"

If (OH: subsample ID) is blank, OR if it contains "ABC", then the calculated field should return the result "XYZ" … I have no idea how to put that in syntax …

I can get two separate lines, but I can't combine them into a command line …
= YES ((OH: Subsample ID) "Header line", "Audit")
= IF (ISBLANK ((OH: Subsample ID)), "Audit")