Can someone please help explain how to do this type of question since we didn't cover this in class
The mass difference gives you the mass of water that has disappeared into the air. The mass remaining gives you the mass of anhydrous sodium sulfate (no water of crystallisation, see equation). Divide each by their relative masses to get the mol of both components of the formula. Simplify by dividing through by the mol of sodium sulfate (to make that value = 1) You now have the mol ratio, which is x.