Respuesta :
Answer:
A = 55
Explanation:
The atomic number is the number of protons also = the number of electrons, so basically we have 29 neutrons, 26 electrons and 26 protons. Anyway, it's asking the mass number which is the neutrons + the protons, so you just take 29+26 = 55
Atomic number=26
Neutrons=29
Electrons=26
Mass number=Proton+neutron
Protons=26
Mass number=26+29
=55