I am using MSBNX (microsoft's bbn software) and I caot figure out how it makes its calculations. This is what my network looks like. 
The probabilities for rain are: Yes-> 0.2 , no -> 0.8 JakesLawn wet and rain -> 0.9, not wet and rain -> 0.1, no rain and wet -> 0.2, no rain and not wet -> 0.8. TracyLawn rain and wet -> 0.9, rain and not wet -> 0.1, no rain and wet -> 0.2, no rain and not wet -> 0.8. Now if i set tracylawn to observed wet I get this: 
How is the the chance that it rained, 0.5294, calculated here?