To determine the number of neutrons in an atom, you need to subtract the atomic number (which represents the number of protons) from the atomic mass (which represents the sum of protons and neutrons).
In this case, the atomic number of element X is 30, indicating it has 30 protons. The atomic mass is given as 57. Therefore, the number of neutrons can be calculated as follows:
Number of neutrons = Atomic mass - Atomic number = 57 - 30 = 27
So, there are 27 neutrons in element X.