Make Sum Calculate BLANK cells as 0

Hi Everyone,
in my attachment, I do not get a sum total cells F18 & F19 when cells are blank and get the #value! error,
is there any make the these total cells calculate blank as 0??? the blank cells have their respected formulas which are accurate, need help to make F18 & F19 also calculate blank cells to give a total without getting an error,
please help.



Thank you in advance,
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