How can a Balanced equation give you the mass of a Product from a given Mass of a Reactant

-First balance the equation -Find the Relative Formula mass of the Reactant of the Product and Reactant you need -Find how many moles there is of the Substances you already know the mass of -Using your balanced equation, find how man moles will be made of the other substances -Use that number of Moles to finally find out the mass