Looks to me like you are mistaking mass of the solution with mass of the solute. Yes, mass of the AgNO3 is 72% of the mass of AgI that can be produced from that AgNO3, but it has nothing to do with the question.
Note: don't use LaTeX for whole post, use it just for formulas (and not for chemical ones, unless really necessary). It looks better that way.
Radeford, can you post the original question without translating it to English?