I don't understand what you are saying here. what doex x12/z12 stand for?.
It seems as though you are trying to find the solution for a formula whose
dependance is on x and z? Please provide a sample problem.

Thanks,

Derek

Ane wrote:
Can I use excel to find y = f(x,z)? I have data for y1-y2 ,x1 -x12 and z1 -z12.

Thanks,
Anne