if 15.6 g of hydrate is heated and 11.7 g of anhydrous compound remain, what is the experimental percent by mass of water in the hydrate?

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's. 

It’s b each orbits at a slower rate than the rate rate which the moon orbits the earth