What is 15ww solution?

I think you may have misspelled your question. This always makes it a bit more difficult to answer. But I'm going to make the assumption that your solution was labelled "15% w/w" Is that about right? Well, then, what that means is that your solution contains 15 parts by weight of of the solute, and 85 parts by weight of the solvent. For example, a solution of 15 grams of salt and 85 grams of water is a 15% w/w solution of salt in water. By the way, w/w means "weight in weight".