"bj" wrote...
maybe
=if(or(c43=0,C43+G43=0),0,g4/c43)
....

The OP was confused when giving C43+G43=0 in the origin example formula.
That formula didn't come close to matching the prose specs. There's no need
to check C43+G43=0 unless the OP doesn't want instances of C43 < 0 and C43
= -G43 to result in 0 rather than -1. Off the top of my head, I can't think
of any reason why the OP would want 0 as result instead of -1 but would want
other negative ratios when C43 is nonzero and has the opposite sign of G43.