Balance The Following redox reaction using oxidization number change method (a)fe2O3+CO-fe+CO2(b)kr2Cr2O7+H2O+S-KOH+Cr2O3+SO2

Fe2O3 + 3CO ==> 2Fe + 3CO2

Note I corrected your Kr2Cr2O7 to K2Cr2O7
2K2Cr2O7 + 2H2O + 3S ==> 4KOH + 2Cr2O3 + 3SO2