working out mass no and atomic no of an element?

Question

of an atom which has half as many protons as Si (mass no. 28) and 6 fewer neutorns than atom of Si (mass no 28).

Give symbol, mass no, and atomic no

Answer 1

you got that wrong mate, Si has 14 neutrons so 14-6 would make it have 8 neutrons with its 7 protons making it N 15

Answer 2

14/2 = 7 protons

28 - 6 = 22

N-22? That would be rare!