Question

How the masses on the left and right hand of equation get balanced in positive beta decay. Like P gives neutron and positron.

Answer 1

Like this $X^{n}_k \to X^{n}_{k-1} + e_1 +\nu$

The decay of the proton in the nucleus occurs due to the weak interaction in accordance with the equation $p_1 \to n_0 + e_1 + \nu$