Why do you subtract the mass of the solute from the total mass desired when making mass percent calculations?

Why do cells appear different in distilled water than they do in 10% salt water?

In a laboratory, 1.55mg of an organic compound containing carbon, hydrogen, and oxygen is burned for analysis. this combustion resulted in the formation of 1.45mg of carbon dioxide and .89 mg of water. what is the empirical formula for this compound?

Can someone me with 3 and 4 plz. this is for masteries test.