posted by Jake .
balance the redox equations:
IO3-(aq) -> I2(aq) and I-(aq) -> I2(aq)
balance the redox equation:
S2O3(-2) -> S4O2(2-) and I3- -> I-
IO3- + 6H+ + 5I- ==> 3I2 + 3H2O
S2O3^2- + I2 ==> S4O6^2- + 2I^-
(you made a typo; it should be S4O6 and not S4O2 and I balanced it with I2 and not I3 but I2 + I^- = I3^- and there is no oxidation-reduction for this part; i.e., I2 ==> 2I^- is the redox part.)