Answer
See answers.
Work Step by Step
From Table 32-2, we see that the $\pi^-$ is the antiparticle for the $\pi^+$. The equivalent decay is $\pi^- \rightarrow \mu^- + \overline{\nu}_{\mu}$.
Since we just performed an "anti" on a valid reaction, we expect that all conservation laws will be satisfied, but we check them here for the sake of completeness.
Conservation of charge: $-1 = (-1)+0$.
Conservation of strangeness: $0= 0 + 0$.
Conservation of baryon number: $0=0+0$.
Conservation of lepton number: $0=1-1$.
Conservation of spin: $0=\frac{1}{2} -\frac{1}{2}$.
