I still don't think that's right.

You have food and fuel, which is some fraction of the economy - call that F. You have a rate of inflation in fuel and food - call that f. And you have a rate of inflation in everything else - call that e. Then you have

  3.8 = e(1-F) + fF.

I think what you're claiming is that fF = 1.0, so that e(1-F) = 2.8. And I think that's wrong. When they say inflation apart from food and fuel is 2.8, they mean e, not e(1-F).