A radioactive nucleus (initial mass number $A$ and atomic number Z) emits $3\alpha$-particles and 2 positrons. The ratio of number of neutrons to that of protons in the final nucleus will be\\
(1) $\frac { A - Z - 8 } { Z - 4 }$\\
(2) $\frac { A - Z - 4 } { Z - 8 }$\\
(3) $\frac { A - Z - 12 } { Z - 4 }$\\
(4) $\frac { A - Z - 4 } { Z - 2 }$