решите систему x+y=6  
                      x^2-y^2=12                        x-?

believe/ don't believe and why 

1) the world progress 
2) the postulate "Beaury will save the world" 
3) reincarnation (the belief that after you die can be born again as a differen person, animal or thing) 
4) life after death 
5) the idea that all events are predetermined 
6) the idea that love conquers everything 
7) love at first sight 
8) ill luck brought by black cats 
9) the postulate that money and power cannot make you happy 
10) the postulate that every new generation is wiser than the revious one 
11) ghosts and witches 
12) UFOs 
13) magic 
14) horoscopes 
15)yourself

помогите пожалуйста решить а то училка меня прибьёт

вычислите массу H2S кол во вещества 5 моль