Which will form a precipitate cu(no3)2 or cu2s

Cu2S is the one that is going to form a precipitate and Cu(NO3)2 will not form a precipitate because it is soluble. It is a fact that those that are insoluble will form a precipitate. I hope that this is the answer that you were looking for and the answer has actually come to your desired help.

Ok where is the image ?

You would do 1500/4 and the answer is 375