How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain?

The number of protons in an atom is equal the atomic number (= 50)

The sum of the Neutrons and Protons is the Atomic Mass (=125)
Neutrons + Protons=125

Plug in for the protons (50)
Neutrons +(50)=125

Then, once solved, we have Neutrons = 75

Assuming the atom is NOT an ion, the amount of electrons is equal to the number of protons. (protons=electrons=50=50)

Therefore:
There are 50 electrons, 50 protons, and 75 electrons.

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.