Write a balanced equation for each of the following redox reactions in an acidic solution using the half-reaction method:
(a) $\mathrm{Sn}^{2+}(a q)+\mathrm{IO}_{3}^{-}(a q) \longrightarrow \mathrm{Sn}^{4+}(a q)+\mathrm{I}_{2}(s)$
(b) $\mathrm{AsO}_{3}^{3-}(a q)+\mathrm{Br}_{2}(l) \longrightarrow \mathrm{AsO}_{4}{ }^{3-}(a q)+\mathrm{Br}^{-}(a q)$