$x+0 \times 4+x+(-1) \times 4=0$
or, $2 x=+4$ or, $x=+2$
Thus, it is the complex in which the central metal atom in cationic and anionic parts have same oxidation state.
$($At. No. $Mo = 42, Pt = 78)$
$5 {Fe}^{2+}+{MnO}_{4}^{-}+8 {H}^{+} \rightarrow {Mn}^{2+}+4 {H}_{2} {O}+5 {Fe}^{3+}$