Was mass conserved in the reaction of iron and sulfur?

Yes, it is. Mass is conserved in every chemical reaction. This is because the mass of a sample of a substance is equal to the sum of the masses of its atoms, and chemical reactions only re-arrange atoms, they do not create or destroy them. 

Yes it is mass is conserved in the reaction of iron and sulfur.

So what you would do is go through and add 3 teaspoons(tsp) 6 times because of the 6 tablespoons(tbsp). which will give you an answer of 18. another way is to multiply 3x6=18.