Your formula

=IF(And(y=0,z=0),x,z)

will not work unless you are working with named ranges. (Y & Z are
unsafe named ranges because there is the danger of it being
interpretted as the whole columns of Y or Z.)

Using cell references:

=IF(And(B2=0,C2=0),B2,C2)

In the above, if both B2 and C2 equal zero, then the answer will be
zero. If both are not zero, the answer will be whatever is in cell C2.
However, if B2=2 and C2=0, your answer will be zero, making it appear
that no matter what, your answer is zero.


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nbrcrunch