I just wrote a test and will try to remember the question and how I answered it to the best of my ability. It was basically asking the find the mass of reactants from the mass of one of the products formed. My first step was calculate the moles of the product with known mass. Once I had the moles I multiplied this by the molar ratio between this product and each respective reactant. Now I have moles of both reactants, and the next step is to multiply these moles by the correct molar mass of each reactant and this gives you the mass of each. Was my process correct?