The ratio of walnuts to raisins is
The question is missing the possible numbers of ingredients in each cookie. The cookies can get bigger or the batch size can increase, or both, as the ratio gets larger.
But, we know that the ratio of walnuts to raisons is fixed, so as long as the possible numbers maintain the ratio, they are correct.
Possibilities include any unit of measurement that is the same for both ingredients, and any multiple of both ingredients:
I had to stop at