Hi Don R

First check to make sure you have a balanced reaction

Once that is confirmed you should be able to set up a ratio based on the moles in your balanced equation

For Example

Your Equation says that

8HNO_{3}, 8 moles of Nitric Acid makes 4H_{2}O or 4 moles of Water so

4 moles Water/8 moles Nitric Acid = x moles of Water/13.5 moles of Nitric Acid

You could cross multiply to solve for x moles of water

When you calculate x moles of water you can use the molar masses you have listed to convert your moles of water into grams of water

You can also do the same by converting everything into grams first according the moles in your balanced equation, and the moles given, then your answer would be in grams. You will need to use your masses given to calculate the molecular weights, of Nitric Acid and Water.

I hope this helps and by the way if your equation above is balance, it appears mathematically that the ratio of Nitric Acid to Water is 8 to 4 and 8/4 is 2 so the ratio of Nitric Acid to Water is 2 to 1.