$${P_x}\left( X \right) = M{e^{\left( { - 2\left| x \right|} \right)}} + N{e^{\left( { - 3\left| x \right|} \right)}}\,\,$$ is the probability density function for the real random variable $$X,$$ over the entire $$x$$-axis, $$M$$ and $$N$$ are both positive real numbers. The equation relating $$M$$ and $$N$$ is