Another BIOLOGY question please?

Question

32/15P, a radioactive form of phosphorus, has..

a)an atomic number of 32

b)an atomic mass of 15

c)an atomic mass of 47

d)32 electrons

e)17 neutrons

please im totally lost here

and if you could tell me how you found your answer that would be a HUGE help

thanks

Answer 1

E, 17 Neutrons

The number on top, the 32 is the mass number, or the number of protons + neutrons. The bottom number is its atomic number, or the number of protons that compose the element. Therefore, 32/15P has 15 protons, and because 32-15=17, 17 neutrons as well.

Answer 2

It has an atomic number of 15 (equal to the number of protons in the nucleus and electrons around it).  It has an atomic mass of 32 because of an additional neutron in the nucleus (it has 17 neutrons while the standard, nonradioactive version has 16 neutrons and a mass of 31).

I'm just doing this from memory, but all of this should be in a standard introductory chemistry textbook.