The Ruthenium Ru is a chemical element belonging to the Platinum group. If you look on the periodic table, his atomic number is Z=44. Atomic number represents too the number of Protons, and since an atom is electrically neutral, the number of protons is equal to the number of electrons. So Ruthenium got 44 electrons.
The mass number of the ruthenium based on the periodic table is A=101.
A = Z+N with N the number of neutrons. So N = A-Z = 101 - 44 = 57.
So the Ruthenium contains 57 neutrons.
Just for more information, the Ruthenium is commonly used in Jewelry and in electricity in case of severe wear resistance.
Hope this Helps! :)