OK.
It seems you want to start with qx=Bc^x where B and c are to be determined from a statistical procedure and x is and age (time varying) subscript. I think that’s like what’s been called a Spillman-Mitscherlich function
Using Excel terminology, I’d write it as q(x)=B * c^x.
Maximum likelihood isn’t that hard for this case, but I think a more standard approach would be to transform the equation into an easier to handle linear form and then use linear regression, which Excel is well equipped to do.
So if you take logarithms (natural, base 10, or any base you like) of both sides, your equation becomes
log(q)=log(B) + x*log(c)
Using Excel, you can list your known values for q down (say) columnA, list your known values for x down columnB and then use an Excel regression to obtain values for log(B) and log(c). These can then be transformed back to get B and c, i.e. the values you want.
For Excel regression, you can use the one in the add-on statistical analysis pak (if you have this) or use Excel’s LinEst function, either via VBA or directly from the Excel worksheet. If you’re not familiar with LinEst you can find out plenty about it from the Excel Help.
Putting together you own regression using the standard Excel tools isn’t that hard either.
If your ideas on logical purity bother you sufficiently that you feel the urge to get B and c directly rather than retransforming them from logarithnms, then you could use alternative statistical techniques such as Maximum Likelihood or Empirical Characteristic Function. But, as you point out, unless familiar with these you may find them more complicated.