Question

$$\begin{gathered} \stackrel{(+7)}{Mn}{O}_4^{-}→M{n}^{+2} ,5e^{-} gain                     \left(1\right) \\ \stackrel{(+3)}{C_2}{O}_4^{-2}→\stackrel{(+4)}{C{O}_2},2e^{-}  loss                       \left(2\right) \end{gathered}$$
multiplying (1) by 2 and (2) by 5 to balance e^{–
$2Mn{O}_4^{-}+5C_2{O}_4^{-2}→2M{n}^{+2}+10C{O}_2$}
on balancing charge;
$2Mn{O}_4^{-}+5C_2{O}_4^{-2}+16H^{+}→2M{n}^{+2}+10C{O}_2+8H_{2}O$